I Purchase few live rock today, (please review photo) this one particular rock has alot of hitch hikers. 4 clams 3 inches long , Orange coraline algae , some plant growth , and next to one of the clams this particular critter I cannot identify . I am wondering if any of you came across this type of critter? I dont think it's a clam if you view the picture closely there is a pinkish (mouth) opening which opens and closes from time to time.