Geometrid caterpillar

Since I started to photograph nature, I came across a lot of amazing critters, including some stunning caterpillars. But this one went straight to the top, it is easily one of my top five caterpillars of all time. It's body is covered with greenish protuberances that make it look like a piece of lichen. An extraordinary example of mimicry. Last photo shows how it was when I found it, looking like anything but a caterpillar.