New Species found?

These odd crustaceans were found in an under ground river in the Russian city of Chelyabinsk. According to the source the one in this photo is about 4 feet long, but there is no way of actually telling. I have not had any luck finding any additional information on this. But I will keep searching. Does anyone have an idea what this could be? It's not a horseshoe crab, its a bit different from that actually, and its fresh water...
If any one has some information please fill me in, i have been raking my brain over this for nearly a month...






