Acid-Enuts are a sub-species of Nep-Enuts from New Super Mario Bros. 8. They are like a Blargg, or, as said above, a Nep-Enut, but made of acid, they will have the same battle strategy as a Blargg, but spit a acidball before sinking back in the acid. They appear in Cogs of The Acid River, a level in Industrial Stronghold.
They are invincible and cannot be killed.