The Leatherback Sea Turtle is the largest turtle in the world, weighing approximately 900kg. Contrary to appearance, the leatherback doesn't actually have a shell. What looks like a shell is in fact a leathery skin supported by small bones. This gives it a flexibility that a solid shell would not provide, allowing it to dive to astonishing depths.
A school of fish exhibiting Swarm Intelligence (SI). The fish follow very simple rules, and although there is no centralized control structure dictating how the individual fish should behave - there is yet an emergence of an "intelligent" unified behavior, unknown to the individual fish.