? Switch Panel
From the Super Mario Wiki
? Switch Panels give more time to a ? Switch Event. To trigger the ? Switch Panel, the Yoshi must shoot a Yoshi Egg at the panel to flip it. There are many of them in certain levels. ? Switch Panels also act as ? Switches, so when the Yoshi attempts to flip the panel without pressing the ? Switch first, the event will start normally as if he pressed the ? Switch. When the music becomes sped-up, the Yoshi has little time left in the event unless it flips another ? Switch Panel with another Yoshi Egg.