I have a 10 gallon tank that I want to use for something.
I know most pets don't comfortably live in something so small so I was thinking something like a planted aquarium with just plants or a terrarium.
Sea monkeys are cool as FUCK, honestly. They only live about three weeks and i'm not sure what can live with them, but they're definitely fun as hell to watch and very easy to care for.
I'd say plants, bettas, shrimp, snails, or a combo of them. My ten gal has a betta, some neon tetras, some plants and some shrimp and they're doing great. Some bettas will fuck heavy with any other creatures though, so it's case-by-case. I'm personally really enjoying my setup, but I'm not sure if it'd be harder than a planted tank. Something like a scorpion or a spider could work, too. I don't know anything about bugs, but maybe you could look into that or some other anon could help you.
>a planted aquarium with just plants
I find it easier to keep a plant tank looking nice if there are shrimp and snails in there to clean up the algae. It also means you have to worry less about fertilizing.
If you don't want anything flashy, you could get a couple Amano shrimp and black nerites.
Ten gallons is pretty small for most vertebrates, but there are some small fish or frogs that would be comfortable in a tank like that.
my 10 gal has a male betta and 3 von rio tetras with a live moss in there as well, with a heater and a filter bettas are extremely active and curious and they're a lot of fun to watch, i highly recommend it
The small tank could be modified into an external filter (submerged or fluidized bed) for a bigger aquarium.
But animal suggestions:
* Heavily planted tank with small shrimps and one male betta
* Aquatic invertebrates like backswimmers, water scorpions, daphnia, diving beetles
* Hissing cockroaches / Death's head cockroach
* Praying mantis