Batoidea is commonly known as rays. They are close relative to the sharks and have well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces.
One of them is the Manta ray. The larger species reaches 7 m in width while the smaller reaches 5.5 m. Mantas are found in warm temperate, subtropical and tropical waters.
More information on Ray can be found on Wikipedia.