My teardrop maxima has been closed for the past two days. Everytime I went to check it out I saw one of my shrimps picking at the shell from the top, but they have done this before. The clam is now open, mantel completely retracted into the shell and it wont close when I touch it with a pair of tongs. All other clams are fine. Is my clam dead? If it is I want to take it out before it ruins the water. Hope you say no.