Snail babies

[jamos5790]

In my 12 gal I have @10 snails of different types turbo,vibex, and others. Today I noticed on the glass 2 very small snails that looks like Turbo/Astrea Snails, my question is how do they reproduce and how long does it take?
Also those snails ride around with each other alot so are they just riding or are they reproducing when they do that?

 

[jamos5790]

When i said they ride on each other I meant the large ones not the small ones.