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.

Splounders will either move 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 will throw Plessie off course if bumped into. Jumping on a Splounder can provide a very decent bounce, and 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.

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