Hi everyone! I have a snail who has been quite lethargic recently. The past two times I’ve looked at him he’s been holding pieces of gravel (still not sure what that’s about). Today he had this weird bit of green on the side of the shell, looks like it’s more on the inside than outside. I’m not sure what it is or if I should remove it. Any help would be greatly appreciated! He’s not a new snail, has been living happily in the tank for about 4 months now.