Stone Spike

Stone Spikes are a sub-species of Spikes that first appear in New Super Mario Bros. Wii. They are blue in color and have green hair (the opposite of Spikes' coloration). They act like normal Spikes, but are found in mountainous regions and throw spiked balls made out of rock.

New Super Mario Bros. Wii
In New Super Mario Bros. Wii, they are found in World 6-1 and in World 8-4. Unlike normal Spikes, Stone Spikes can only throw their spiked balls downwards, rather than forwards or backwards. They can be defeated just like normal Spikes: by jumping on its head, by throwing a fireball at it, or by freezing them using an Ice Flower or a Penguin Suit.

New Super Mario Bros. U
Stone Spikes reappear in New Super Mario Bros. U. Their behavior is similar to New Super Mario Bros. Wii, although there is an aesthetic difference in that their rocks are colored dark brown. They appear in the level Dry Desert Mushrooms in Layer-Cake Desert, where they are the main obstacles.

In New Super Luigi U they appear in Stone Spike Conveyors where they once again are the main obstacle.

Mario Party: Island Tour
Stone Spikes reappear in Mario Party: Island Tour as well, but their only confirmed appearance is in the minigame Mad Ladders.

Trivia

 * Their color scheme resembles both Tubba Blubba's and Grubba's.