Shell (flashing)

A Rainbow Shell is a rare kind of shell found only in Super Mario World. If a Beach Koopa climbs into a Yellow Shell, even if it's not its own, it will become invisible, with its shell flashing rainbow colours (turning it into a Rainbow Shell) and attempting to hit Mario (or Luigi) by spinning around in its shell. Mario can only defeat with a Spin Jump, Star, etc. If Yoshi were to eat a Rainbow Shell, he would temporarily get all three shell abilities: make small earthquakes, fly, and spit out fire.