Reflecto is a Mermaid Man and Barnacle Boy TV series villain, although never seen, but he is mentioned in Mermaid Man and Barnacle Boy. When SpongeBob and Patrick pretend to be Mermaid Man and Barnacle Boy, they pretend that Squidward is Reflecto, "summoning" a jellyfish on him, which Squidward blows away. Then they cover him under a tent, only to get an annoyed Squidward to rip it into pieces and chase them.
Since SpongeBob and Patrick pretended that Squidward was Reflecto becuase of the sun mirror, he may have armor made of mirrors or a mirror as a shield.
Because of his name, he may have reflecting powers and may be invulnerable when exposed to a very sunny place.
As SpongeBob mentions, he becomes weaker when he exposed to a shadowy place.