I’m overly fascinated by this, so bear with me.
4 fundamental forms [sunburt, W, ones with a big triangle, and the ugly ones I can’t in any interesting way]
2 are identical after reflection, 2 not = 6 basic shapes after reflection. 7-fold symmetry ==> 6*7 = 42 ways to dissect the heptagon into triangles = C7
I miss combinatorics. Catalan numbers are fun :D