Large Sea Purse (Big Skate, Raja binoculata?)

Observation by Mike Brubaker:

Have never seen a purse this big before on McDonald Spit. Can someone help determine species?

Comments from LEO Editors:

Sharks, skates and chimaera's are oviparous species, meaning they lay their eggs in cases which are deposited on the seafloor. After the embryo has developed, it leaves the case, which then may wash up on a nearby beach. In a NOAA publication "Where do baby skates come from", fisheries staff provide photos of the egg cases produced by skate species in Alaska. The egg case in the photo appears to match the one produced by the Big Skate (Raja binoculata). According to the Florida Museum Big Skate Species Profile, Big Skates produce egg cases measuring 9-12 inches in length and 4-7 inches wide. These large egg cases typically hold 3 or 4 eggs. Erica Lujan