Aetherium Block

Wherever Shimmer meets another liquid, the boundary hardens into this. It happens on its own around the Aether pool and it happens the moment you start pumping water into a shimmer setup, which is how most people meet it: a wall of blocks appearing exactly where they wanted flow.

It is as slick as ice. Stopping takes a run of extra tiles and turning around takes longer still, so a floor of it will throw off any fight you try to have standing on top. Ice Skates or anything built out of them cancel the problem completely. It lights itself, which makes it usable as a floor that needs no torches, and it sheds small star particles when you stand or run on it.