I was given one assassin snail, and it must have been a pregnant female, because within a month (approx.) of getting it, I saw the first pinhead sized baby. Now I have at least a dozen 1/8-1/4" assassin snails. I find the really tiny babies blend with the sand and are nearly impossible to see unless they sit on a white rock or light green leaf. Also, I no longer have a pond snail problem and am actually thinking of importing some to keep the assassins fed.