Dash Coins (also known as Hidden Coins) are coins in that have appeared in multiple Super Mario titles. They appear at first as transparent circles. When Mario or another player passes through the circles, they become coins and this means that the process must be repeated to collect the coins. Dash coins vary in how easily they can be found.
Super Mario Odyssey
Dash Coins reappear in Super Mario Odyssey, but rather than being outlined like in the 2D entries, the coins are completely invisible, and lack an outline. But if you groundpound near them, you can see a coin-shaped reflection in their place. Collecting them, though, is still the same; you have to interact with them twice to collect them. To fit the exploration gameplay in Super Mario Odyssey, these coins are found in more obscured parts of an area