Friction

This is one side of an unused angle grinder disc, a very much more used one was used to cut the steel yesterday. They are basically a composite matrix with hard abrasive bits in, you spin them at around 10 000 rpm, and the friction from the disc cuts through things. They aren't sharp or have teeth like a saw, and they aren't even particularly tough - they are designed to wear away as you use them, but they do cut through hard things like concrete or in my case old steel.

It's also naturally black, so works well as a mono image. No flowers, but plenty of power...