Pokey

Pokeys are yellow cactuses made of several segments with a head as the top segment with red eyes and a mouth that appear in Super Mario 64. They deal damage upon contact. They are defeated by jumping on all of their segments before they can regenerate more segments, or jumping on their head, which will immediately kill the Pokey. It drops a blue coin upon being defeated. They only appear in Shifting Sand Land.

Headless Pokey
Seen in Super Mario 64 DS is an anomaly where Pokeys appear with no head, likely due to a malfunction in the Personalization A.I.