Vantablack, made by Surrey NanoSystems, is a coating of vertically grown carbon nanotubes. Light that enters the "forest" bounces between the tubes until it is absorbed, so the surface reflects just 0.04 percent of incoming light. Wrinkled or curved objects coated in it look like flat black holes.
via UK scientists develop super-black material that absorbs 99.96 percent of surface light | New Atlas