Hello! I’ve had simple tanks around the house for years and have always loved them, but lately I have been trying to jump into live plants, aquascaping and (intentional) snails. I have three nerites currently that have been in quarantine for almost 3 weeks with daily water changes and very close care. They’ve consistently been very active and explore the quarantine tank, pick at whatever foods I give them and climb all over each other. But last night I noticed this white thing coming out of the side of my Zebra Nerite (I’ll attach photos). I’ve never seen it before and I’m scare it could be something bad that could harm the little snail or one of the other two in the quarantine tank. It does seem to move a little, and when I tried to reposition the tank to get a better photo (the one from the underside) the white thing retracted into the shell. I’m very nervous and feeling quite overwhelmed at the idea of not knowing how to make sure/ actually make the little snail safe if it is in fact dangerous. Any and all advice would be so so greatly appreciated, I’m really desperate here!