Mystery Snail and a white substance?

[krenner]

I've had my mystery snail in a planted 10 gallon with a betta and a recently added bristlenose pleco. The tank walls have enough algae (the pleco is given a shrimp pellet so he doesn't steal all of the snails food), and now that he's gotten used to the betta swimming up to him, he doesn't randomly drop off the walls. He's very active and healthy, and I can see him eating, but sometimes I notice at his mouth chunks of a pure white substance. He's my first snail that I actually bought (finally killed off my pest snails that inhabited this tank!) so I'm not incredibly knowledgeable. I can't really tell if this is something that he's making, or if he's scraping calcium off the tank? I went to take a photo before I posted and watched him eat the rest of it in one big bite. He's obviously having no issues, but I really wanna know what it is, and if it's safe/normal for him to be eating it. The tank is pretty clean and well filtered, so I'm iffy on if it's calcium scrapings because I'm not entirely sure where he'd be finding it in such large chunks.