How much life there is in the world, and how much there has been.
There's one tree that's super old, a bristlecone pine that is 4,841 years old apparently. Apart from that outlier, there would be next to nothing that's seen the last millenia through still alive today, at least compared to the living things. It's beautiful how the world has developed into how it is today; If someone ate an apple 100 years ago and threw out the core, assuming all went well there would be another tree there. The cycle continues, and the little deaths of the tree's fruits lead to uncountable lives being created and sustained.
Let's say that in a few years, or months, or days, the tree gets struck by lightning and falls down. Unfortunately, this leads to its death. But all is not lost! Mushrooms grow around it, breaking down the matter into nutrients for other plants to use. And from that, trees and plants, ferns, everything gets fed better from one little loss of life.
I think that that is beautiful. How the web of plant life can feed itself, and in the process sustain the lives of countless animals. There is so much beauty in the world, and I really love it.