The Crab Monsters are creatures that debuted in "Rising Tides, Crashing Skies".
The Crab Monsters look like normal crabs, albeit with noticable anatomical deviations. They are orange and white. They have two claws and six legs. They have one spike at the top of their heads. They have only one eye just like the Crab Gem Monster.
They only appear twice in the episode. First when Ronaldo is recreating the Gem Warship crashing, one pinches Ronaldo's hand. The second time is when the Crystal Gems are fighting the Crab Gem Monster. It is unknown what happened to them after the Crab Gem Monster was poofed.