MSC
Natural Pearl Lover
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Nautilus pearl
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la_corsetiere
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That conch pearl is mesmerizing!
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Natural's posts have been moved to a new thread "Various Natural Pearls" as they are off the Nautilus topic and deserve their own page. https://www.pearl-guide.com/forum/showthread.php?t=8174
Lagoon Island Pearls
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I have cross replied to this thread; Tom Stern's natural pearls. as not to derail it.
Indeed the dilemma is acute. Clearly empirical data on the topic does not exist, but in the absence of it, conjecture is all we have.
Nautilus shells are structured with hexagonal columnar aragonite, hence it stands to reason nautilus pearls could better described as "columnar". Source: Crystal Habit
Without trying to be pedantic, the term non-nacreous is too vague, especially for our purposes. A brick, a dog or a peanut butter sandwich are non-nacreous objects yet have little or nothing to do with crystalline structures. The term is a disambiguation perpetuated by the cultured pearl industry to apply to any pearl apart from "terraced" aragonite structures. Even in the most calcitic of pearls, I very often find them enclosed in nacreous linings.
We know woefully little about nautilus habits. For example, no one has described reproductive behavior much beyond the spadix and fecundity (copulation and fertility rate). It's known nautilus reproduce annually once they reach maturity at an average of six to eight years of age. They produce only about a dozen eggs each time as observed in captured animals. They do not replicate nesting behavior while in captivity, even following maximum gestation. No human has ever observed the active laying and tending of a nest, nor has the period of time been established. Some speculate only a few weeks, while others suggest upwards of nine months. Either way, it's astounding that a sea creature which only produces a hundred eggs in it's lifetime has not gone extinct. Most other fish produce eggs by the thousands and shellfish by the millions. To me, it's seems probable a highly toxic element is involved to defend the nest from predators.
Nautilus are the longest living cephalopod. Fifteen years at most. Octopus dofleni live five to six years and giant squids only five hundred days. Couple that with the fact nautilus are largely pelagic (swimming), abyssal (deep) and scarcely epibenthic (near the bottom), the rate of occurrence of pearl anomalies are astoundingly low. While we have observed blisters from shell damage or misplaced septums, the incidence of free pearls remains an elusive endeavor. With that, I can only suggest our best bet for finding pearls from shelled cephalopods lay with fossils.
We have ammonite mines on Vancouver Island. I really need to set up an expedition sometime in the future. I am aware of holes found in some specimens, but were difficult ascertain as to their cause. In the absence of growth fronts, I can only assume they occurred post mortem. I'll revisit that paper for clarity on the issue.
As always Steve, I'm looking forward to seeing continued reports.
Indeed the dilemma is acute. Clearly empirical data on the topic does not exist, but in the absence of it, conjecture is all we have.
Nautilus shells are structured with hexagonal columnar aragonite, hence it stands to reason nautilus pearls could better described as "columnar". Source: Crystal Habit
Without trying to be pedantic, the term non-nacreous is too vague, especially for our purposes. A brick, a dog or a peanut butter sandwich are non-nacreous objects yet have little or nothing to do with crystalline structures. The term is a disambiguation perpetuated by the cultured pearl industry to apply to any pearl apart from "terraced" aragonite structures. Even in the most calcitic of pearls, I very often find them enclosed in nacreous linings.
We know woefully little about nautilus habits. For example, no one has described reproductive behavior much beyond the spadix and fecundity (copulation and fertility rate). It's known nautilus reproduce annually once they reach maturity at an average of six to eight years of age. They produce only about a dozen eggs each time as observed in captured animals. They do not replicate nesting behavior while in captivity, even following maximum gestation. No human has ever observed the active laying and tending of a nest, nor has the period of time been established. Some speculate only a few weeks, while others suggest upwards of nine months. Either way, it's astounding that a sea creature which only produces a hundred eggs in it's lifetime has not gone extinct. Most other fish produce eggs by the thousands and shellfish by the millions. To me, it's seems probable a highly toxic element is involved to defend the nest from predators.
Nautilus are the longest living cephalopod. Fifteen years at most. Octopus dofleni live five to six years and giant squids only five hundred days. Couple that with the fact nautilus are largely pelagic (swimming), abyssal (deep) and scarcely epibenthic (near the bottom), the rate of occurrence of pearl anomalies are astoundingly low. While we have observed blisters from shell damage or misplaced septums, the incidence of free pearls remains an elusive endeavor. With that, I can only suggest our best bet for finding pearls from shelled cephalopods lay with fossils.
We have ammonite mines on Vancouver Island. I really need to set up an expedition sometime in the future. I am aware of holes found in some specimens, but were difficult ascertain as to their cause. In the absence of growth fronts, I can only assume they occurred post mortem. I'll revisit that paper for clarity on the issue.
As always Steve, I'm looking forward to seeing continued reports.
Caitlin
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This is a great post on nautilus and thank you so much for using the terms in parentheses to help us learn this vocabulary.
I think your ammonite mine idea is fantastic. They have a lot of ammonites for sale in Tucson at the gem show every Feb. Is there something I can study or learn in order to look at some specimens intelligently or even ask questions of the sellers?- some of whom do know something about fossils. Perhaps I could do some kind of survey of what is available.
I think your ammonite mine idea is fantastic. They have a lot of ammonites for sale in Tucson at the gem show every Feb. Is there something I can study or learn in order to look at some specimens intelligently or even ask questions of the sellers?- some of whom do know something about fossils. Perhaps I could do some kind of survey of what is available.
SteveM
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Good idea, it also occurred to me but I've gotten a bit out of practice…
Actually Nautilus is unique among mollusks in producing nacre of both the columnar (gastropoda, predominant at the Nautilus' aperture and septa) and terraced (bilvalvia, predominant in the mid-chamber walls) types, in addition to about every other transmutation of aragonite biocrystallization. That's what keeps the conjecture going, and a study of the literature on Nautilus shell microstructure is practically endless.
But what a fascinating study it is! Peter Ward's out-of-print 'In Search of Nautilus' is a history of the research through the mid-'70s, Ward's early adventures reading like a Hemingway novel. As for low fecundity and apparent endangered status, there are certainly Nautilus populations that are rapidly diminishing but I am among those who believe that fishing is effectively driving Nautilus back to the sea depths that resulted in its miraculous survival of the K-T asteroid extinction event (unlike the dinosaurs and practically everything else) in the first place.
Supposedly loose pearls would be ejected from the ammonoid/nautiloid aperture unless attached to the shell—which would only occur in the final chamber during the years following the mollusk's maturity. Fossil evidence for blisters is fairly common, from Housean Pits to more recent sensationalism surrounding DeBaets et al, to a personal contact with Dr. Helmut Kupp in Berlin, who kindly sent me his otherwise-unavailable work on ammonoid pathology from the 1980s. But the most satisfying bit of detective work was uncovering and obtaining an original print of Alois Kieslinger's Nautiloid blister (external shell, NOT an impression as with House's pits) from a scientific expedition to Timor in the early 20th century, its pearl blister closely corresponding to a shell with blister in my collection, still awaiting dissection. If only we could find that fossil (which may yet reside in a Dutch warehouse containing artifacts from the expedition in question)!
This was a very pleasant way to get things back on track. Work by competent and renowned scientists continues (thank the mystique of Nautilus) so there is every likelihood of further news at some point.
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Lagoon Island Pearls
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That certainly supports my assertion that virtually any mollusk with a valve or valves are nacreous, if only in the lining. Even the tube worm Serpula vermicularis lives in a nacreous lined calcareous tube which is attached to a rock, shell or any other hard surface. It's an annelid, not a mollusk at all. It's what the vicera (guts) prefers and all adductors (muscles) attach. Nacreous layers over prismatic layers are the norms among most clams, mussels, oysters but scallops stray from it somewhat. Usually toward calcitic structures. Nacreous layers over columnar layers would indeed be very rare. The SEM's are not back from the lab yet concerning Pododesmus macrochisma (Jingle Oyster aka Rock Oyster), but I'm certain it's transparent nacreous layers over foliated layers in both shells and pearls.
Lagoon Island Pearls
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Agreed. Like gastropods, they function with much of their mantles outside the shell. Merely extending could easily expel a growing pearl. Cephalopods especially! They extend their musculature in micro-thin layers. They're for the ability to escape through the tiniest of cracks and scuppers. In the rare event a pearl nucleus gets past the septum it may or may not perforate the outer epithelium but would almost invariably become stuck to the shell nonetheless.
Wouldn't That be something to peel back the layers of ammolite to reveal a fossil of a nautilus pearl? Most fossils as we know them are molded replicas of their former selves by other minerals, where ammolite was buried in sediments that prevent the aragonite from converting to calcite. Depending on the region, it will likely be mineralized where the protein was with pyrite, calcite or silica.
I wonder what that would do to the structure of the pearl?
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SteveM
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Nacre from an annelid sounded odd to me so I took a quick look and was impressed to learn of Serpulidae's use of organic sheets and aragonite ? la nacre. However it seems that the similarities to actual nacre, i.e. aragonite platelets uniformly sized, shaped and positioned by microscopic perforations in a preceding organic membrane, end there.
That brought me to Vermetidae, a gastropod family creating tubes with a nacreous inner lining.
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SteveM
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The putative Nautilus pearls in this thread could never become ammolite, which is petrified nacre. That said, just think if a nacreous pearl could be transformed as was this hefty chunk of ammonite aperture!
A rare specimen, 100% gemstone:
Ammolite is most typically a two-dimensional gem, united with its matrix of petrified sediment. A loose pearl would first have needed to survive the decomposition of the mollusk to be enveloped in the protective sediment, and then only the outermost layers of aragonite would be preserved. The ammolite pearl, if it existed, would be lost in the midst of the rock that forms the interior of a potentially priceless ammonite fossil.
But it would be beautiful in its maker's eyes.
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dmj
pppp pearl
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yeah i was able to buy a nice nautilus argo shell with big blister this week as well only the seller wanted a stupid price pretty sure another pger bought it now since its sold already ( hope he will post some pics soon ) 
pretty happy with the polished nautilus with long blister in there first one i bought that actually has a look like it s a pearl
pretty happy with the polished nautilus with long blister in there first one i bought that actually has a look like it s a pearl 
GemGeek
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Nautilus are simply not large enough to host a growth of immense size and the pearls are extremely rare and hard to prove origin.
If it is a pearl, and not carved out of shell, it is much more likely to have come from Tridacna gigas, but this is highly unlikely. Anything of size is usually attached to the shell and not round. Honestly, what you are showing looks like it was carved from shell. Try shining a single spotlight above it to look for a "ring of fire" flame pattern that might indicate that it is a pearl.
The first photo in your post looks like an operculum and not a pearl at all. Can you tell me what the post number was?
If it is a pearl, and not carved out of shell, it is much more likely to have come from Tridacna gigas, but this is highly unlikely. Anything of size is usually attached to the shell and not round. Honestly, what you are showing looks like it was carved from shell. Try shining a single spotlight above it to look for a "ring of fire" flame pattern that might indicate that it is a pearl.
The first photo in your post looks like an operculum and not a pearl at all. Can you tell me what the post number was?
