Rockworms were small subterranean Rahi that were carnivorous and poisonous. The first Rockworms were created by the Makuta species using Viruses and Liquid Protodermis. An army of Rockworms once attacked Po-Koro, which Pohatu defended by kicking boulders into the oncoming Rockworms. Another encounter took place when Takua wandered into a cave filled with Stone Rats. Jaller then tried to rescue him but they both fell into another cavern that was filled with Rockworms instead. The two Matoran then had to dig themselves out to the surface.