creatures like this existed on earth in its early years. look at the primitive eyes. it is amazing how life evolves. there is life flourishing elsewhere for sure.
http://blog.wired.com/wiredscience/2009/02/freakarthropod.html?npu=1&mbid=yhp
http://blog.wired.com/wiredscience/2009/02/freakarthropod.html?npu=1&mbid=yhp