This is obviously a crab. What's interesting about it is that it's sitting in reinforced concrete, that was made to look like wood, and that it's currently on a mountain, around 2000m.
This was the second little fellow we met - I managed to scare the first away before Nora managed to get a picture, so I was happy to meet one more. It's still strange to find crabs on mountains for me though.
(Oh, by the way: this entry was written by Peter Molnar, and originally posted on petermolnar dot net.)