Bros. Block

From the Super Mario Wiki

A Bros. Block is a special block only found in Mario & Luigi: Superstar Saga. It is a yellow block with an arrow on it. When struck by either Mario or Luigi, it will move in the direction of the arrow and change to the opposite brother's color and initial. When struck by that brother, it will move back to where it was and change again. Striking Bros. Blocks take speedy timing, as there are usually 20 coins in each one. However, if the brothers are too slow on their jumping, less coins will earned.

Blocks

! Block | ? Block | ♪ Block | 4-Bros. Random Block | Arrow Block | Aurora Block | Bonus Block | Brick Block | Bros. Block | Coin Block | Command Block | Control Block | Dice Block | Dotted Line Block | Drop Block | Egg Block | Event Block | Expansion Block | Giant ? Block | Giant ! Block | Grab Block | Heart Block | Hidden Block | Hint Block | Ice Block | L Block | Laser Block | M Block | Marshmallow Block | Metal Block | Minus Block | Mushroom Block | Perry Block | Pink Block | Plus Block | POW Block | Pushing Block | Rally Block | Random Block | Rock Block | Save Block | Shine Block | Simu-Block | Spin Block | Star Block | Stone Block | Super Block | Triangular Block | Turning Block | Used Block | Warp Block | Wooden Block | Yellow Block | Yoshi Block