Are these pearls?

[Smaureen]

Hi! I'm new here and wondering if someone can help. We found these in my hometown but don't know if they are pearls. I really appreciate your help!

 

[Pearl Dreams]

I see shells, not pearls.

 

[BWeaves]

Here's some questions you can ask yourself when someone offers you items like these.

Do they look like pearls to you? (no)
Would you string them and wear them around your neck? (no)
Or would you use them as a doorstop? (yes)
Do they look like shells? (yes, and they're not even pretty shells)