A kind of robot created by Alien Mimy, designed from repurposed warships that sank to the seafloor. Many Iron Rocks appeared before many Terrestrial Defense Force bases around the world. The time bomb inside them made a huge explosion and caused immense damage to the surrounding coastlines.

In Japan, an Iron Rocks made from the famous Japanese Battleship Yamato appeared suddenly from under the sea. It sank the Kuroshio-maru No. 3 around the coral atoll Marcus Island, and then appeared near Shimoda Port which sent the town into panic. Iron Rocks disappeared into the sea for a time, but resurfaced when the Ultra Guard arrived. It was unaffected by both land and aerial attacks and even shot down Ultra Hawk No. 3, but it was immobilised after a direct overhead attack and activated its time bomb.

Ultraseven arrived only to be immobilized by Iron Rocks’ chains and then injured by its cannons. Ultraseven cut the chains with his Rolling Spark ability and fired an Emerium Beam which set Iron Rocks on fire just before its timer was about to explode.