I was bashing apart an old zoa rock to keep just the corner with the last viable zos on it when the rock unexpectedly split in two, shot across the table and made one heck of a mess. When I collected the two halves I was amazed at what I found. One rock had something mahogany in color and shaped like a overly long woman's fingernail sticking out of it. I looked at the other half and there was a perfect hole where that half sticking out had obviously lived within that rock. It seemed like the rock was sealed as it was one that someone had made. I tugged carefully on the mahogany piece and it slid right out which surprised me! It felt like a very light stone, so I was lightly drying it and one side of it cracked. So it had to be some kind of clam. I wished it wouldn't have cracked. It could have lived in the tank sand or something. The hermits made quick work of the flesh inside. Has anyone ever run across anything like this ever before? I have to say, it was pretty neat finding it there, but I never intended to kill it.