Mine

File:Floating Mine.PNG

They don't explode

Floating Mines first appeared in Super Mario World as spiked balls that drifted in the water in various levels. They follow the current continuously and pulsate with spikes. Yoshi can step on their spikes hramlessly and a Starman can defeat them. In the Sunken Ghost Ship many are in free fall making it difficult for Mario to move around.

The Mines reappeared in Super Mario Land: 6 Golden Coins as a spiked ball spinning around a bubble in the final stage of the Mario Zone.