Bramballs are an enemy which mainly appear in the Jungle/Forest levels of New Super Mario Bros. Wii and New Super Mario Bros. U. Their heads are like Pokeys, with thorny, spiky branches, and yellow suction cup feet. They stick to the top of blocks, flipping itself over which is its only way of moving. Touching any part of the Bramball will hurt the player, while the player can hit its head in any way or use the Star to defeat the Bramball.
 Johnnie's tips
I'd go under them, and wait for them to flip themselves away from you.