Is it ok for your clam to sit on your sand bed? He came on my live rock and stayed there for months but now is moving. What bothers me is that its mouth down in the sand. It is open right now and if I touch its shell it closes. By the way it has anchored its self to the base rock. I moved it yesterday very carefully and by morning its almost right back in the same spot. So if its ok i;m going to leave it. Thanks.