This is a broad topic for a challenge because the details of pictures are almost always interesting regardless of the subject matter. I have seen so many wonderful postings on this topic already. In spite of the many submissions, one should not get fooled into thinking that capturing the details in a picture is always easy to do. In fact, this objective requires you to get beyond simply finding the focal point for the picture, to thinking about the depth of focus needed to capture the details across the entirety of the object of interest, and then making sure you have the right set of conditions and parameters for your shot. This is particularly challenging for closeups. I think I have been fortunate to be able to capture a few such pictures. You can make the judgement. So here goes!
I like to get close up to see the details on butterflies, but sometimes it more difficult than you actually think it is because you do not get the depth of focus needed. Sometimes the butterflies cooperate by presenting a flat surface.
I like trying to capture the details of the various plants and flowers in their natural surrounding. Here are a couple of examples that I liked.
Finally, here are a couple of pictures that are really not the best quality, but I liked the subject matter a lot.