Richard Dawkins famously said "Biology is the study of complicated things that give the appearance of having been designed for a purpose."
Let's begin by illustrating the claim. Some seashells and snail shells are very "artistic." They rival human sculpture and decorated pottery. Likewise, camouflage. Some snake skins have patterns that rival Persian carpets.
Without sufficient background knowledge, an observer couldn't tell which was designed and which was not.
There are, however, two problems with that comparison:
i) It proves to much. Suppose we reverse the logic: shells and snake skins weren't designed; therefore, sculpture, decorated pottery, and Persian carpets weren't designed!
ii) For a Judeo-Christian theist, contrast posits a false dichotomy. It's true that shells and snake skins are natural products rather than manmade artifacts. They weren't designed in that sense.
But that doesn't mean they weren't designed at all. In Judeo-Christian theism, nature and design aren't two opposing principles. Rather, God usually produces an effect through an intermediary.
It's like robotics: we make machines that make machines.