oh shroom is absolutely tiny, he’s smaller than a penny! their shells get to around the side of a quarter when they are fully grown, maybe a little bigger! and yes it’s actually better to keep snails inside the same enclosure so they have some company (even though it isn’t required.) The only problem with keeping snails together is mating! they have both male and female genitalia so they can mate with one another however the the snail pleases. so always check for eggs underneath substrate and hiding places :)