The Treasure Chest Crab is a crab creature created by Dr. Robotnik through the use of the Chaos Emerald of Life. In the times of Pirates, a lonely treasure chest lay buried on Shark Island with the Chaos Emerald of Invisibility inside. After a scuffle with Sonic the Hedgehog, Dr. Robotnik obtained the Chaos Emerald of Invisibility and then used the Chaos Emerald of Life to transform the treasure chest into a living crab creature. The Treasure Chest Crab ate Sonic, trapping him inside himself. Tails befriended a female crab and got her to bat her eyes at the Treasure Chest Crab who dropped his jaw, allowing Sonic to escape. The last time the Treasure Chest Crab was seen, he was being chased by the female crab, angry and swinging a rolling pin.