What is depicted in the picture?

I Googled it, which was well worth doing. I found more and better images than the one here. The pupa is a cool thing! The elytral margins are the 'plates' that Rafter mentions, and they cover the wings, a thing not obvious from photos. This answer is almost straight from Wikipedia.

I took a picture of one on one of my hikes in one of my state's many protected forests (NY). Too bad we couldn't post one pic.

It's a beetle that thinks it's a turtle, of some kind...

is it harmful😯