Well, I don’t know if this will help, but reading these comments it seems like a good idea to use the terrain manipulator to make your own entrances to caverns on planets with no entrances ?
I’ll have to try it and report back, to see if it helps with finding that last creature.
BTW My first planet (after restart) had a tiny, tiny butterfly on it. It was barely bigger than the red/green dot. I assumed I’d see more, but haven’t yet.