After I cleaned and rearranged my hermies home the other day, one of them promptly buried herself! This is a good thing! It means she is molting. Not to be confused with changing her shell.
Hermits are decapod crustaceans, they have their own shell or exoskeleton, except in the most vulnerable spot, the abdomen. As a result, they take over outer shells left abandoned by other sea creatures. As they grow, or sometimes by whim they change these shells.
Once a year or so they molt. They bury themselves in damp sand and break out of the exoskeleton and the new one takes a few days to harden. They are VERY vulnerable to attack, especially from other hermies, at this point, so we need to be VERY vigilant and keep a close eye on her this week or so. I might even remove the hermies that aren’t molting to a covered plastic shoebox until she emerges from the sand.