The Shellcreeper is a turtle-like enemy that first appeared in Mario Bros.. Like the other enemies from Mario Bros., if the player doesn't kick the Shellcreeper before it gets up, it will turn a different color and move at higher speeds. It will get faster and faster each time it is flipped over.
The Shellcreeper would appear on the Mario Bros. stage. When they are attacked, they will retreat into their shell and can be used as throwable items. They will cause very large horizontal knockback and makes it easy to defeat opponents. If there is a Munchlax on the stage, it can eat a flipped-over Shellcreeper.
 Trophy Info
Shelled enemies Mario and Luigi faced back when they were plumbers. They had to be bumped from below to flip them over and then kicked off the stage. The last one on a stage turned from green to red and raced really fast. If one got flipped but not sent off, it would eventually right itself and move at high speeds. They were simply called "turtles" in Japan.