Three kinds of blood vessels are arteries, vanes and caterpillars. The pistol of a flower is its only protection against insects. The purpose of the skeleton is something to hitch the meat to. A permanent set of teeth consists of eight canines, eight cuspids, two molars, and eight cuspidors. The tides are a fight between the Earth and moon.
All water tends towards the moon, because there is no water in the moon, and nature abhors a vacuum.
I forget where the sun joins in this fight. The older it is, the more extinct it is. A menagerie lion running around the Earth through Africa. A nest of young puppies. Something you find crawling all over a dead cat.