Porcupines are found in Mario Kart 64. They appear in the middle of several paths in Yoshi Valley. If a racer hits a Porcupine, their kart will spin out. They resemble Porcupo from Super Mario Bros. 2, which are purple in Super Mario All-Stars and Super Mario Advance.
In the Mario Kart 8 rendition of the course, the Porcupines have been replaced with Goombas.