https://en.wikipedia.org/wiki/Common_Surinam_toad

Probably the glass frog or the Suriname toad for maximum body horror. Glass frog so you can see your own guts and Suriname toad so that your eyeballs are on the back of your skull and constantly are looking at your own ass. Darwin's frog is pretty fun too, looks weird and barfs up their babies, btw the babies shit in your mouth the whole time they're gestating, definitely best to be female here cause they don't have to deal with babies shitting in their mouths. But hey if you're male and one of the babies dies you get a tasty snack

I like frogs, eldritch little freaks