I was emptying the scrap bin some months ago and came across these two little snails in the middle of what I think was snail sex.
I had never witnessed this event before and found it to be extremely fascinating.
Below are some images, which, if you have ever wondered about how snails have sex, may answer your question.
There is a YouTube clip with a snail laying eggs which is really interesting also. They lay their eggs in a hollow under the earth.