The gel uses sea pearls to refract light, almost like having lots of tiny mirrors on the skin.

And when it was analysed conservators found that it was not a surface designed to refract light at all - it was soap.

His crystal body acts as a prism that can refract light and energy beams.

These shapes, like a prism, can refract light in specific directions.

However, all these disturbances refract light rays, so they can cast shadows.