Wonder how the figured out that they were intelligently designed? Didn’t think that sort of thing was possible /s.
For an explanation of how we know those prismatic blades knapped from a polyhedral core were "intelligently designed", see my explanation in #23.
Those blades are not at all easy to make correctly, and doing so takes at least as much planning and motor skill as "running the table" in pool...
FWIW, such blades, knapped from a truly glassy material such as obsidian, have the sharpest edges ever made -- far sharper than the best surgical steel scalpel.