If I had photographs of piles of leaves from different forest types – and some of the piles in different photographs were from the same forest type – and I was only able to identify the leaves by geometry and color and not by their name – and the leaves had deteriorated so much that I couldn’t use any traditional geometrical classification to identify them by their shape – though they all had a unique shape, what type of math could I use to group the photographs by forest types? What if the leaves pretty much all had the same shape – though they were known to be different and from different forest types, and the only information that I could use to identify the leaves was a video that showed that different leaves changed their shape at different rates while they were deteriorating.