purchased a crocea 2 weeks ago .things were great he attached opened and closed and every day more mantle seen.i feed my tank dt's every other day and my other clams are doing great under vho liting.the other day i noticed after adding some acro frags near him he had spun on his foot then the next day found him upside down on the bottem of the tank.repositioned him on rock and he was down upside down again.put him in a nook where he could expand with out any neighbors near and 4 hrs later his shell has opened and mantle is pulled back from edges of shell by 1 cm.this clam is about 2.5" long.is he checking out.i feel bad because i pride myself on good husbandry but something was bad in his immediate environment.this doesn't look good .is there anything to do but theraupetic neglect.any input appreciated.thanks beach.