what do snails eat?

[Bartman]

I picked up a couple snails from this agriculture park type place near me for my sav I took one baby one and i couldnt feed it to him causs i felt to bad since it was still only a lil guy

Just wondering what they eat and how to keep him alive..thanks!

heres a pic, its just like a common snail i guess..what would it be called?




Ill try to get a more clear picture if needed for the identification..

thanks!