I know for a fact my mystery isn't carrying eggs because I've had it for months in a 2.5 g alone and only yesterday put it into a 10 g with 2 other snails. One of the other snails is just hanging out on its shell and won't come off no matter what. So then the snail came up totally out of the water under the filter output, so there was still water flowing on it. Is this a breeding thing or should I be concerned that my snail is trying to get out? Oh, I forgot to mention that the water level is lowered just in case eggs do appear
Mystery snails often crawl out of the water for reasons only they understand. The aquarium should have a tight fitting, full hood and an inch or more of moist air between the hood and water surface.