Humans also lack color receptor adaptations for ultraviolet rays. They are shaped as a reference to the rays of the sun. Sea stars are prey for sharks, rays, and sea anemones. This is derived from geometrical optics, based on the assumption that light travels in rays. Technetium-99m emits only gamma rays and decays to technetium-99. Sterilization by irradiation with gamma rays may however affect material properties. This abundance difference is a result of the way secondary cosmic rays are formed. These radiations were given the name "Becquerel Rays". The class includes sharks, rays and chimaeras. This material is nonallergic, nontoxic, antibacterial and resistant to UV rays. ECC memory is used to protect data against data corruption caused by cosmic rays. These "calorific rays" were later termed infrared. Batoidea is a superorder of cartilaginous fishes commonly known as rays. Industrial Radiography can be performed utilizing either X-rays or gamma rays. There is no consensus for a definition distinguishing between X-rays and gamma rays.