I am debating on buying at a store in Oklahoma City, an hour and a half for me. They only have 1 clam. It has a blue mantle with some strange striations, I have no idea what type it is. Very nice colors I think. What do I need to look for as in a "healthy" clam? It is open nicely under their 175 MH. Whenever I moved my hand under the light, the mantle seemed to close a little, this is a good sign right? It is about 3 to 3 1/2 inches across.