A slightly less well-known bit of Pythagorean goofiness was their elitism about the dodecahedron. The dodecahedron is probably the least intuitive of the five Platonic solids, and when the Pythagoreans figured out that it can exist, they got a little goofy about it. They were already sort of mystical about their numbers, and they assigned elements to each of the five aforementioned solids. The thing was, they didn't tell anybody outside of the cult about it, you only learned about it if you reached the Pythagorean Thirty-Third Degree or something. Apparently they thought that all hell would break loose if the great unwashed knew that you could build a twelve-sided polyhedron out of regular pentagons.
Carl Sagan said that one guy tried to publish the existence of the dodecahedron - however that was done in a paper-minimal society - but was suppressed and thrown out of the Pythagorean cult. Later, the guy died in a shipwreck, and people in the cult said that he only got what was coming to him. The similarity of this story to legbagede's seems to indicate that either people drowned at sea regularly, or that the Pythagorean cult has reached mythical status.