This weekend I got out clamming for the first time this year, and I was very lucky to find my second ever quahog pearl on the trip! Sadly, the shell was not visibly warped on the outside (as many pearl-bearing quahogs are) so I boiled the clam, which caused a slight hairline crack to form on its surface. The pearl didn't warp the shell because it was in a really strange place - inside the hinge itself! You can actually see the shape of the hinge imprinted into the pearl. Here are some photos.

http://imgur.com/a/uKx1zT2