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yeah
Hypocycloid is a diamond shape like the three on the helmet of the football team Steelers. Hope this helped :)
tetracuspid/ hypocycloid
An astroid is a hypocycloid with four cusps - a particular form of plane curve traced from a fixed point on a circle.
Hypocycloid. from Wikipedia: "a special plane curve generated by the trace of a fixed point on a small circle that rolls within a larger circle."