Just an idea that sprang to mind :D
Space Slime
-Black and translucent
-Falls from the sky at night rarely
-Since they're falling from space, you have to vac them up before they hit the ground. If they hit the ground they explode similarly to a tarr.
-Diet: fruit
-Favorite Food: Moonfruit (bet you thought I was gonna say starfruit. Well that would work too)
-Like a puddle or fire slime, they can't be made largos
-Plort: Black translucent with white sparkles like stars with a purple "gemstone" in the middle
Unknowns:
-Slimepedia entry
-Actual picture
-Would they need a special pen or could they live in a normal corral?
-Plort price: Since these slimes are rare, the price should probably be up pretty high at the start. 350 newbucks or so?
-Places they would spawn (Maybe add a new spot to the map? ;)
Thanks for reading! If anything else comes to mind I might post it here.
-LazyPotato