Rupees

Rupees are a type of collectible in Super Luigi Country, only found in Level 8. They sport a yellow-ish/gold-ish color scheme and are the main currency in The Legend of Zelda series.

Level 8
In this level, there are 23 Rupees spread across the map for you to collect, a Peahat will follow while your trying to collect them and Dixie Kong will fly through to top part of the level trying to hit you. Collecting them all will spawn in a Star.

"Fake" Rupees
In Level 11, three fake Rupees can be seen resting on a platform that is also fake, these Rupees play along with the japes in the rest of the level.

Trivia

 * The Rupees in Super Luigi Country are based their design in the original Legend of Zelda for NES.