From the Super Mario Wiki
Tail Thwomp is a Thwomp with a Tanooki tail that appears as an enemy in Super Mario 3D Land. They act very similar to Grindels and Thwimps.
Tail Thwomps can jump about in a wide set area, unlike the regular stationary Thwomps; because of this, Mario has to pay close attention to their movement patterns in order to avoid being flattened. When they float about, it is reminiscent of the way Tanooki Mario floats, complete with the accompanying sound effect. Unlike normal Thwomps, They only have a face on one side, due to the tail on their back. Tail Thwomps can be defeated by transforming into Statue Mario and either landing on them or having them land on him, like normal Thwomps. Only two appear in the entire game and they both appear in World 5-1.
Names in other languages
||Roca Picuda Tanuki