The Rapid Crabs resemble fairly standard crabs. They have red armor with a gray underbelly and four legs with red tips. They also have small black eyes and long pincers with gray finger tips.
The Rapid Crabs appear exclusively in Coral Cave and on Hidden Islands that share the Coral Cave motif. In gameplay, the Rapid Crabs scuttle back and forth on their own. When the player approaches however, they will stop and start thrusting their claws into the air for a few seconds before resuming their scuttling. While they trust their claws into the air, the player will take damage should they attempt to attack them from above with a Spin Jump/Axel Jump. However, they are easily dispatched with a Super Boost/Fire Boost.