i happened to look into my tank and seen this. there is green stuff on my snails back,could the other have been eating it? i thought they were mating,but i don't know

it does look like they are trying to mate. are they male & female? here is a pic of my snails mating:



the male inserts his penis under the female's shell.

honestly,i'm not sure. i just know the basics of keeping them. when it comes to breeding,i'm clueless.

it looks as if they might have been mating from that pic. if you find red sort of tiny balls covered in what looks almost like hard jelly, then yes, they did mate!!

how long does it usually take for the eggs to appear?

It depends on your water quality, food availability, and general health of the snail. They will lay eggs within.. a day or so if they're in optimal conditions. If not, females can store sperm for up to six months.