This is the Pacific Football Fish, a denizen of the deep sea that's almost never seen intact. But this unlucky feller washed up in Crystal Cove State Park in Newport Beach, California.
From the park's Facebook page:
There are more than 200 species of angler fish worldwide and this particular fish is most likely the Pacific Football Fish. Only females possess a long stalk on the head with bioluminescent tips used as a lure to entice prey in pitch black water as deep as 3,000 feet! Their teeth, like pointed shards of glass, are transparent and their large mouth is capable of sucking up and swallowing prey the size of their own body. While females can reach lengths of 24 inches males only grow to be about an inch long and their sole purpose is to find a female and help her reproduce. Males latch onto the female with their teeth and become "sexual parasites," eventually coalescing with the female until nothing is left of their form but their testes for reproduction.
H. sagamius lives in the Pacific Ocean at depths of 2,000 to 3,300 feet, where sunlight doesn't penetrate. Food is scarce in the deep, and chance encounters in total darkness are rare, so the footballfish have evolved to feed on whatever fits in its mouth—including other fish, squid, and crustaceans. Using its esca as a lure, an anglerfish remains motionless until prey comes within striking distance. In a lightning-fast motion, it sucks the prey into its mouth, where its teeth—which point inward—ensure that what goes in doesn't come out.