Red Yoshi Star

From the Super Mario Wiki
A Red Yoshi Star

A Red Yoshi Star[1] is an item that appears in Yoshi's New Island. Unlike their their normal yellow counterparts, when a Yoshi collects it, he turns into Super Yoshi and is able to blast through enemies and walls. The effects wear off after a short while, though Yoshi can maintain them by collecting more Red Yoshi Stars.