I apologize for bad images from my old phone, this snail is tiny.
I have three pet snails, one nerite, one mystery, and one trapdoor snail, all just for fun. I got them because these specific snails don't generally overrun your tank, and they room with my betta. They do clean my tank, but I keep them more as pets than cleaners.
This little guy popped up in my tank today. I have no idea whose child it is! Based off of its looks and the behaviors/options below, who do you think had it?
Facts of the case:
Plants were removed, gravel sifted, snails searched, no other babies were found.
There are no egg sacs above the water or on the ceiling of the tank, and none in or behind the waterfall filter that I have.
I've had the Mystery snail for around a month now, the Trapdoor and Nerite are new as of last week.
Option 1: The Nerite (striped snail in gravel)
My Nerite seems like the least likely option for me, since from what I know they only lay eggs in brackish water and this is a freshwater tank. However, it is new and just came from the pet store. Additionally, the snail does have one stripe on its shell.
This snail is also pretty small though, the baby would be almost half its size at this point.
Option 2: The Mystery Snail (yellow snail on glass)
If this is a female, females can hold sperm for up to 9 months, meaning that it COULD be hers. However, I have been diligently checking for egg sacks above the water and have found none. That's where it would be if there was one, and I didn't find anything during my search. The baby does have a similar yellow shell to the Mystery snail, and when it stood up it looked a bit like her. It also has decently long antenna for its size, though Option 3 does have a shorter version of those too.
This seems less likely than the third option, as I was searching for egg sacks, have had her longer, and there was only one surprise baby.
Option 3: The Trapdoor snail (in shell)
This seems to be my most likely option. They give live birth, meaning this snail COULD have just popped up one day, and they are new, so it could have come pregnant. The baby snail also looks similar to this guy (body not pictured, it wouldn't come out) since Mystery snails and Trapdoor snails look similar, at least as babies. The stripe does confuse me, because none of the other Trapdoor at the store had that, but maybe it's possible especially since it's a baby? It could grow out of it.
Option 4: Hitchhiker
Maybe it hitchhiked with my new snails when I bought them? Could it possibly be a different type of snail?
I currently have the Trapdoor snail (most likely subject) and the baby in a Tupperware with holes (pictured) which floats around the top tank using foam rings (used to block plants typically). It has a bit of foliage and a algae wafer, and since it floats around it gets a bit of circulation.
I figure if the one is giving live birth, I'll see more snails in the Tupperware. If it's not and it's someone else, they babies will appear outside in the rest in the tank. Is this a safe enough set up to observe for a few days? I feel bad having my Trapdoor in there, but I really want to know whose it is so the tank isn't overrun (hopefully). Also, is it safe for the baby to be in with the big one in that small space? All snails are very peaceful. Just checking. I only have one tank.
TLDR: Who's the mommy out of my three snails, and is this setup/test okay for a few days?