I want to see more critters in the ocean, or in another and better idea different types of aquatic type critters in different biomes, for example, jungles have tropical fish, or sky lakes have some made up fish(?), and snowy biomes have arctic variants of fishes. I know they are (or I heard) they are adding dolphins but I would like to see more expansions on the ocean. for example, you can make like aquariums and stuff. like that would be lit. I would love a tank of colorful tropical fishes in my world. another good idea is possibly turning some fishes caught easter eggs or references.
I'd love to see a raccoon in the forest, a bearded-dragon-type lizard in the desert, and a macaw in the jungle.
It'd be really cool if there was a capturable mutant critter in the corruption/crimson as well. An awful fleshy blob with too many spines/eyes, but a small enough one to stick in a cage and leave in a corner for the rest of time.