Its breath-taking. I was recently reading about the way deciduous trees shed their leaves; and the entire thing is this incredibly choreographed process.
Nutrients in the leaves are reclaimed in a specific order, then cells along the shear line secrete a hormone that dissolves the glue holding them to each other.

The weakening of the walls of those cells, coupled with increasing internal water pressure inside the cells, causes the cells to swell. This expansion generates tremendous shear forces, i.e., pushing and pulling on surrounding weakened cell walls, mechanically opening up fracture lines between cell walls. Wind tugging on the leaves helps these fracture lines to grow, as do gravity, precipitation and animal interference.

The tree is simultaneously building up a thick layer of sealant over the exposed end of the twig, to protect it from insects and the cold after the leaf has dropped.
The reclaimed nutrients are stored in the rest of the tree, and re-used in Spring to grow more leaves.

I'd always just known it as, something that happens; but like with so many other natural processes; the closer you look at it, the more incredible it is.