First, a bit of history: when I first bought plants long ago, garden-variety pond snails came with them. When they got bad, I bought three assassin snails because that was all the LFS had. For a while I would find lots of pond snail shells but the number of living snails didn't seem to be diminishing, but eventually the assassins started to breed and they overcame the pond snails.

Lately, I've been seeing something new. Tiny snails that appear seemingly from nowhere when the lights are out and then disappear when they're on. There are hundreds of them.

Picture quality's not the best but you get the general idea. There's an adult assassin snail in the middle of the top picture. They like to hang out on the glass and on my mechanical filter media.

My best guess is that these are baby assassin snails. They've got the right shape, you can sort of make out the stripe, and if they were anything else that would mean there are adults breeding somewhere that neither I nor the assassins have found. But, if so, that means at this point I've got an assassin snail infestation that's arguably as bad as the pond snails ever were, which I find sort of funny. What do you think? Assassins, or something else?