This post breaks my heart. You can see my clam at the front of the tank in this video.
https://www.youtube.com/watch?v=Iy3WRBRsBcA
My 29 has had a horrible algae outbreak and pretty much all my corals died. My clam is fine, but in order to fix the 29, I scrubbed my clam's shell clean of the algae and moved him to my 14 and he is not liking it. He was fine for the first few days, but the tank is crowded and i suspect my clownfish has been nipping at him because he has started to close up. I simply don't have the space for him right now which is really upsetting since I've had him for a couple of years.
He is a brown clam, but the underside of his mantle is a metallic green.