So I have been buying pepperment shrimp to combat my aptashia problem I will always get a batch of three alot of times they will molt and i will find the shell flowing around or in my pallys The tank is about 5 years old I i know i have a couple old bisttel worms or fire worms that are large.Now my last set of pepperment shrimp have turned up missing no shell it like someone removed them from the tank no parts floting or anything.Has anyone else had the seen this in the past.