Only two pearls in the world are officially recognized as originating in a cephalopod, one from Nautilus and the other from Argonauta, both owned by Dr. Tom Stern, Nautilus certified by GIA based upon anecdotal evidence and educated supposition vs. objective science. Certification is rendered suspect by vociferous non-concurrence from the other top pearl labs due to skepticism regarding the possibility of a non-nacreous pearl from what they consider to be a nacreous shell. We are therefore obligated to state that the composition and appearance, if not the very existence of Nautilus pearls, remains to be confirmed!
Yes, which is exactly my situation with respect to authenication. Having personally collected each and every pearl from the animals themselves, does not quantify or excuse the claims made by others as to what is natural. In fact, I find most of these claims frustrating. In my case of pearls from M. californianus, anectodal evidence is coupled with objective science, because I can return to one of many sites and find a natural pearl in situ, any given day of the week (weather, tide and licensing permitting). Not so with my octopus pearl. There is nothing to compare it to.
In all honesty, I never gave it much thought initially, mainly because it appeared porcelaneous as opposed to nacreous. Until reading this thread, I had no idea how important the find is, which is why I'm eager to have this pearl examined by experts.
It is not at all like my other natural pearls. Although it's oval from x and y aspects, but the z axis is near perfectly round. Beside the crystalline structure itself, I'm greatly curious to know what is at the nucleus (if anything).
It bears repeating here that every historic mention of Nautilus pearls, going back to Rumphius centuries ago, describes them as porcelanous. In the ongoing search for specimens, there is no credible source in the entire Western Pacific proposing a nacreous example. This is a conundrum in and of itself, as the Nautilus shell is indeed approximately 70% nacreous between its outer and inner prismatic layers.
Concretions are 100% of the case in the operculum of most snails, especially Turban Snails (Turbo petholatus) which are commonly used in first nations art from this area. Operculum is a genetic factor in all animals of the species, but pearls are an anomaly, hence the probablility of varying crystalline structures.
The photo of the mussel section attached earlier in the thread, clearly indicates different color and composition of natural pearls, within millimeters of each other in the same mantle of a single specimen.
But assuming we are beginning to learn something here, the range of Nautilus pearl candidates is certainly comprised of whole pearls, with button being the most common shape, at least among those choice specimens sporting the polar swirl feature.
Parasitation: Predation vs. parasitation seems to be another unique possibility with Nautilus, as the literature includes examples of shells that have been penetrated by drilling from octopus, or Nautilus itself.
Yes. However, there exists a plausibility of a third factor, blood acid-base balance, where no trauma or parasites are present. Even in humans, immunology is not all that well understood, no less in rare invertibrates. Given the nautilus' niche in the environment, the likelyhood of finding one (especially nacreous) is infantesimal. That said, all the more reason to continue searching, diligently.
It seems to me, short of examining thousands and thousands of rare animals for an even rarer occurence within them, our best bet might be to experimentally "culture" cephalopods. The sacrificed animal which yielded mine, was an over-mature male (amputated hectocotylus) thus adding a few extra years to it's lifespan. Enough time for a pearl to form. Octopus are crafty little creatures, though. It would not suprise me in the least they would untie or tear sutures and remove the implants.
On a side note, but interestingly enough, the term "hectocotylus" was coined by French biologist Georges Cuvier in the early 19th century, who first found one embedded in the mantle of a female argonaut, supposing it to be a parasitic worm. I am curious to know, if the blister in the pictures posted in this thread represents this theory. Again, without knowing much about the nautilus, I assume it's lifespan is near the end following copulation, as in other cephalopods, so the possibility of pearls forming from this foreign tissue is unlikely, but might be a result of an unsuccessful mating.