I think it's a Guitar fish on it's back. Or an alien from the planet Zoltar, I have caught a few of those...they gave me an anal probe. They determined that there is no intelligent species on our planet...
Actually it is in a different family than skates but close.
Guitarfish- probably Shovelnose
Family- Rhinobatidae, Genus-Rhinobatos, species- Probably productus but there are several that look pretty much the same. That one seems to be a female and it has been slightly mutilated to give the appearance of eyes.
Fairly common, I have caught several between San Francisco and Monteray. Taste a bit like scallops.
I once saw a picture on the cover of some tabloid of a dried one they were claiming was a Chupa Cabra.lol