Splounder

Splounders are flounder-like enemies that first appear in Super Mario 3D World. They are present in every Plessie-themed level, with the exception of Deepwater Dungeon. Their name comes from "splash" and "flounder."

Splounders will either move from side to side or remain stationary. They can be defeated by almost any attack, even by just coming in contact with them. They do not directly harm the player on contact, but they will throw Plessie off course if bumped into. Jumping on a Splounder can provide a very decent bounce, and it can sometimes even lead to Plessie reaching previously inaccessible areas.

In the Bowser's Fury campaign of Super Mario 3D World + Bowser's Fury, regional, cat-like variants of Splounders appear near the Wasteland Giga Bell, which are now possible for Mario to encounter without riding Plessie. Splounders cannot be defeated by a jump or Ground Pound and hurt Mario on contact if he is not riding Plessie. While boomerangs thrown by using the Boomerang Flower do harm Splounders, fireballs thrown by using the Fire Flower simply phase through them.

In the Super Mario Mash-up in Minecraft, Axolotls are replaced by Splounders.