Money Bags

Money Bags are creatures in Super Mario 64 that look like a regular coin, but when you get close, they turn into their true form. Money Bags hop around, trying to dodge Mario, until he punches or jumps on them, making real coins explode out of the destroyed enemy. It also makes one of the weirdest sounds in the game when defeated.

There's only a couple in the game and one of them is in Snowman's Land.