But I love this story...
In the original story, the monolith was a glowing diamond. The effects people couldn't get it right, so they put a black rectangle on all the storyboards to indicate that they'd come up with a replacement eventually.
Sone day someone looks at the rectangle and says that it would look good. The build one and hell yes, ti looks great.
Movie comes out and all the critics and fans try to figure out what the monolith represents. Is it the Bible? A tombstone? What???
Years later, the original writer, Arthur Clarke, is doing a Q+A and some snotnosed punk stands up and tells Clarke that he's figured it out.
The monolith is in the ratio 1 : 4 : 9, the squares of the first three numbers.
Clarke loves it, and puts it in the next book.