I began an experiment a few days ago where I put a single ramshorn (my original) into a vase filled with dechlorinated water and small bit of an algae wafer. Then I waited.
In the first 24 hours it laid a single clutch of eggs. But I woke this morning after not checking for a day to find SIX MORE. Six. There are no decorations for a clutch to hide on, and I just changed the water for him.
SIX clutches of eggs, with an average of 28 eggs per clutch. Somebody's been busy!