Octopus
Reference: Cephalopod eye
Three hearts, blue blood, eight arms, no bones — and a camera eye built entirely separately from ours that is wired better than ours is.
Scored on every axis
The eye that has no blind spot
The vertebrate retina is inverted: nerves and blood vessels lie in front of the photoreceptors and the bundle must punch through the retina to leave. That hole is the blind spot, and every vertebrate has one.
The octopus arrived at the same lens-and-retina camera eye by a completely separate route, and got the wiring the other way round — photoreceptors facing the light, nerves leaving from behind. No hole, no blind spot.
It focuses by moving the lens like a camera rather than deforming it as we do. And, remarkably, it is almost certainly colourblind — one photoreceptor class — in an animal that changes colour constantly and precisely. It reads polarised light, which we cannot; one published proposal is that the odd pupil shape lets it extract colour from chromatic blur, though that remains a hypothesis rather than a settled finding.
A body with one hard part
Three hearts — two for the gills, one for the body, the last of which stops while swimming. Copper-based haemocyanin instead of haemoglobin, so the blood is blue and works better in cold, low-oxygen water. No skeleton apart from the beak, which is why an octopus can pass through any gap the beak fits through.
Most of its neurons are in its arms rather than its brain, and a severed arm continues to behave purposefully. Whatever the octopus is doing, it is not doing it the way a vertebrate does — which is the point of including it on the same axes as a horse.