At first glance I assumed this was a ray of some kind because of its wide body and lack of fins, but after going back to take a second look I realised it must have been a shark with the fins and tail cut off (as seen on the right). A friend of mine informs me that it's a shovelnose shark (or more correctly, shovelnose guitarfish), which another friend just told me is a type of ray anyway! So it looks like my first thoughts were right all along. A little digging on Wikipedia turns up its proper name, rhinobatos productus, which is indeed part of the ray family. You learn something new every day :) Despite its size I almost stepped on it without realising it was there - the wind was quickly covering it with sand.