My guess is they might say neither is a case of design--both types of polished stones result from the same physical processes and produce smooth, sort of roundish shapes. It's different when a person sculpts a stone and smooths the resulting shape (except maybe in the case of some works of modern art).
How about comparing Mt Rushmore with the Old Man of the Mountain (before he fell down the hill)? Or a bust of Julius Caesar with a potato that looks like Richard Nixon? Despite William (Look at me--I'm Isaac Newton) Dembski's claim to be able to quantitatively identify design (his "explanatory filter"), it still strikes me as a matter of finding patterns where you look--in clouds, inkblots, or entrails. The situation is rendered problematic because we are familiar with how human designers come up with designs, but not how other designers do it. In other words, the alleged designs we see are what we might expect of human designers.
