Without being able to smell it and feel it knowing how big it is (there is no frame of reference as that plate could be a saucer) and how long it was frozen for and how, it's really hard to say with 100% certainty whether this is beef, lamb, pork or dinosaur meat. ;-)
However it contains bone, fat and meat, so add some butter in a kettle, throw the meat in and lightly fry it on all sides, add your favourite spices, a bottle of dark beer and roughly chopped onions and let it boil in the beer with a lid on the kettle until the meat falls off the bone, and come back and tell us what kind of meat it was!
66% chance it's pork though, 22% it's beef that was slightly discoloured by being frozen for too long and a little more discoloured in the top left by bad packing, 11% it's lamb and 10⁻¹¹ % chance it's dinosaur meat. ;-)