Leonardo da vinci understood about 500 years ago that a round valve worked best and most efficiently with 3 parts rather than 2.
Normally we are born with a 3-cusp aortic valve (tricuspid, looking like a "mercedes-benz" logo). Occasionally people can be born with only 2 cusps or a bicuspid aortic valve
-- (looking like the "cbs" logo). A bicuspid aortic valve is more prone to wear out over time.