Huckit Crab

Huckit Crabs are a species of red crabs consisting of a shell, two yellow feet and only one claw that it uses to throw either sand balls or rocks. Their goal is to hit Mario and his company with their projectiles, which travel in a straight line when thrown.

New Super Mario Bros. Wii
In New Super Mario Bros. Wii, Huckit Crabs appear only in the third stage of World 4, where they are found in large quantities. Huckit Crabs are stationary enemies that throw sandballs to the left. Also, by throwing, the force of the throw pushes them back slightly to the right. Huckit Crabs can be defeated the same ways as a common enemy: jumping on its head, freezing them with a Ice Flower or a Penguin Suit, attacking it with a Fire Flower, or by running into it with a Starman. The sand balls can also be destroyed, but only by jumping on them, as ice balls and fireballs are ineffective.

New Super Mario Bros. U
Huckit Crabs reappear in the Wii U game, New Super Mario Bros. U. This time, they throw rocks. Also, the rocks they throw can be raised in elevation by a Water Spout.

Mario Party 9
In Mario Party 9, Huckit Crabs appear on the Blooper Beach stage. When the player lands on an Event Space, which appear after traversing half the board, the crabs on a pirate ship fire their cannons, which turn any Mini Stars into Mini Ztars and vice versa. Several scattered Huckit Crabs also appear on the board.

Mario Party: Island Tour
Huckit Crabs appear in various minigames in Mario Party: Island Tour.

Mario Party 10
Huckit Crabs reappear in Mario Party 10 in Whimsical Waters and in some minigames.

Trivia

 * Their name is a pun on "hermit crab" (the crab species they resemble), and the term "chuck it", as they throw sand balls.
 * Their rock throwing technique is very similar to Clawgrip the Crab boss from Super Mario Bros 2.