I wonder if i have a hitchhiker also, I have one area in the tank where there are several astrea shells lying in a group, I've gotten up several times in the night to try and see if there is one, but have never seen one. Maybe I have a snail burial ground, kinda like the elephant burial grounds where all of the old elephants go to die, only with snails. Greg, many times I'll come up to my tank and think one of my cleaner shrimp is dead only to realize it is a molt, kinda throws ya for a second.