Betta fish and Snails

Question
QUESTION: Hi there! I'm just writing in because I had a bit of a question.

I got my first betta fish from a rather sketchy petstore on friday. While I was first cleaning out his bowl when i brought him home, I noticed we had a little friend: a tiny little snail! After cleaning his little bowl completely, I also came across some empty shells.

The original betta died (had a fungus I didn't see on his back when I bought him, and also swim bladder disease that I tried to treat but didn't seem to catch in time), but the snail lives on! Currently, he's in the tank with Dorthy II (aptly named by my baby nephew in honour of Elmo), anyways... is there anything I should be doing to provide for the snail? I've gotten a bigger tank (from the small betta bowls to a 2 gallon tank) and he's mostly stayed under the rocks and pebbles. occasionally coming up the sides for a little looksee above water. He's black and has a little "hatch" for when he's inside the shell... don't know exactly what else to say about him. Dorthy I tried to gobble him up when I was placing him back in the water after he neared the top of the bowl, lol but so far he's going strong xD

Thanks for the help :)

(also, will he get any bigger? If so, will I have to provide him with shells, Like I would a hermit crab?)
ANSWER: the thing about snails they multiply like crazy also they are trap door snails and those get pretty big but they grow their own shell i would try to get rid of them tranfering the betta to another tank is what i would do and they dont need food

---------- FOLLOW-UP ----------

QUESTION: Well I'm assuming it's a trap door snail, I don't really know what to look for.

Would it do any harm to let him grow a bit more before moving him? Will he be in harms way, or cause more harm, if I introdcue a pleco in the tank with him?

Answer
well the betta might eat the snails out of their shell if their is nothing else to eat same with the pleco and almost all plecos get huge i think clown plecos are the smallest plecos around but they need a heater or they will die but they only get about 3-4 inches but snails came become a real problem