From the Super Mario Wiki
Morty Moles are giant sub-species of Monty Mole that appear in Super Mario 3D Land. They resemble Mega Moles, but have reddish-brown fur color and don't wear sunglasses.
Mario stomping on a Morty Mole.
Morty Moles inhabit cave levels such as World 5-4 and 7-4 along with Monty Moles. They are defeated by two stomps on the head, similar to a Rex, and after Mario stomps one once, the rodent gets shorter and faster; on the second stomp, the rodent is defeated. A ground pound will defeat them in one hit. However, if they manage to hit Mario while they are short, they will grow back to regular size. When defeated, Morty Moles will sometimes give Super Mushrooms.
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