Every ocean scientist should know how to tie a half dozen or so knots. One of those should be a monkey’s fist, name because it looks like a small clenched fist, it was originally tied into the end of a line or rope to add weight. The weighted end could be thrown easily over a horizontal yard on a mast or between the ship and dock during tie up. Stories also tell of sailor using them in bar fights. But I and KZ know nothing about that.
They are an elegant knot and you can impress others by making either cufflinks, for those fancy nautical occasions, or as a keychain. I have used them repeatedly as underwater float in polypro line that can be easily grabbed by a submersible or ROV manipulator arm.