Looking for Natural Pearl Information

by Gail

Hi,

While vacationing on the big island in Hawaii, I spent many hours on the beaches and rocky shores looking for shells, I was shocked to come across these three little, I will call them pearls because I'm not sure what they are. They were covered in kinda of an oily film. They are beautiful, they are all different sizes. I am sending a picture.

Any info would be most appreciated.
Thanks
Gail O'Neil