Bones, Brawn & Brains
Fewer than 5% of all animals that ever lived on planet earth have backbones-- yet, we humans remain quite chauvinistic about our own kind. Many of us don't realize that chordates paved the way to US! Their basic animalness – multi-cellularity, a head, brain, nerves, and bilateral symmetry – is the legacy of the sponges, cnidarians, and ancient flatworm-like animals, each of which pioneered pieces of the architecture that led to complex animals like Pikaia, and us.
There's a great deal more to learn from our new chapter on chordates.