Hi everyone! My name is Amanda and I have had my crabs for about a year. I have gone through a few successful molts until now. I had a crab leave his shell and go under... (at least I think he dig down, because I cannot find him). I do not think that he took a new shell down with him. Is this normal? I monitor the humidity/temp so I believe they are ok. I am just worried about the missing crab. Any advice? Am I doing something wrong for them? HELP. And also what does everyone think the best substrates are?