It’s a clam. But it’s a pretty big one. I’m a sucker (umm, pardon the joke) for giant clams. The mantle (that’s the colorful part on top, inside the shell) is different for each one, like a fingerprint. And the colors are often wild. This one was about 4 feet across. They come bigger. But still. All very Jules Verne.
Dive Site: Arborek Jetty, Dampier Strait, Raja Ampat, Indonesia, February 2014