Oh, immune to fire, that's not good for Popp. Hopefully it's not immune to magic, full stop, or else that'll be a real problem. But at least for now, there's still no need for Avan to get involved. Surely his future self gave Popp advice for handling this sort of situation, it's just a question of if Popp internalized it.

"Typically you boil the snail to death if you're cooking it!" he yells from a safe distance, as helpful as always. You're also supposed to starve them for a few days beforehand to purge them of impurities, but that would be even less helpful to point out right now.