10-Coin

The 10 Gold Coin is a special kind of coin that's worth ten coins. It made its appearance throughout different installments of the Mario series and the Wario series.

Super Mario RPG: Legend of the Seven Stars
Coins that are worth ten regular coins first appeared in Super Mario RPG: Legend of the Seven Stars, along with regular coins and Frog Coins. In this game they look just like regular coins, but are bigger than their normal counterparts. 10 Gold Coins sometimes appeared after a larger enemy was bested.

Mario & Luigi: Partners in Time
They also appear in Mario & Luigi: Partners in Time, but instead they are coins with a "10" on the face.

Wario Land: Super Mario Land 3
10 Gold Coins also were present in Wario Land: Super Mario Land 3. In the game, they look like normal coins, but instead of their usual "1" symbol, a cross is stamped on them. They seldom appear after defeating certain enemies in a specific way and when they are collected, they make a unique noise.

Wario can produce this items from his inventory, which will cost him ten of his already collected coins, by pressing the B button and "up" on the directional pad. The coin can then be thrown to defeat enemies. This technique is also necessary to open Goal Doors and completing the Level.

Wario Land 2
The 10 Gold Coin also appear in Wario Land 2, although they are now called Wario Coins. They appear as golden coins with Wario's face stamped on them and they can be quickly distinguished from other coins by their enormous size. Wario's coin counter increases by ten when he picks up a Wario Coin, and they also make a unique sound when they are collected.

In Wario Land 2, coins were used to pay minigames in order to find hidden treasures. Contrary to regular coins that can be found just along the road, Wario Coins are usually stored in secret rooms or remote or hardly accessible locations, to make it harder for the player to obtain them.

Trivia

 * Objects worth ten regular coins also appear in Mario Party. They look like treasure chests in this game however, as opposed to actual coins.