A Tail Thwomp is a Thwomp with a Tanooki tail that appears as an enemy in Super Mario 3D Land. These rocky fellows act very similar to Grindels.
History
Super Mario 3D Land
In Super Mario 3D Land, Tail Thwomps (unlike the regular stationary Thwomps) can jump about in a wide set area, because of this, Mario has to pay close attention to their movement patterns in order to avoid being flattened. When they float about, its reminiscent of the way Tanooki Mario floats, they even make the same noise while doing so. They appear in World 5-1.