I have a 75 gallon tank. which has nassarius snails, 2 turbo snails, one yellow tang,one clown, a clearner rasp, and a fire gobie.The tank has live rock , A sand bed,soft corals, some hard corals. the lighting is a 175W mh and a blue atcinic .The other morning all was well, 7 Hrs. later one of my maxima clams was gone, just an emty shell remaind. Any idea on who could have eaten my clam. HELP Thank you. Tony