He is much better now. He is eating my hornwort and is sometimes crawling around. I am going out to get calcium foods for him this weekend, but until then pellet will have to suffice.
Usually pretty hardy. I like to watch them when they fall off of something and "glide" to the bottom of the tank. how they do that is probably the mystery.
It's a mystery snail to me. They do like decaying plant matter so if yours are decomposing, then that could explain the behavior although hornworts aren't definitely tasty.