Their ancestors were catholic diners, appropriately enough for fish. As well as hawking for insects they grubbed in the mud for shellfish and worms and burrowing crustaceans. Their snouts sport coiling barbels which were first used to locate their prey and later on evolved to root it out and seize it, stronger and more dextrous over the generations. By the time they evolve the powerful brains that make them the object of our study, they have something like a hand of six muscular fingers attached to their faces.

They are quicker to develop than the trilobites or the eurypterids, and one convenient narrative is simply the way that they are bound to the transition between land and water. They now live primarily in fresh water, haunting the river edges, lakes and swamps that, in other timelines, will give later eras their coal seams and industrial ages. These are unstable biomes, always on the point of being too brackish, too anoxic, too dry, too hot. The Devonians evolve on a knife edge of need. Their breeding requires conditions the world is reluctant to guarantee. Even their respiration is conditional on their environment, for by adulthood they have lost their gills and breathe through their skins and the linings of their mouths.

As their intelligence develops it is driven by a need to control and stabilize their environment. They start with dams, dykes and other primitive terraforming, then progress to manipulating the chemical make-up of their surroundings, to which their barbels and skins are highly sensitive. While working with stone and wood, they are also experimenting with salt gradients and the curious bond properties of water molecules. Their alchemists unlock the secrets of electricity frighteningly early. In the cold climes they love, where their respiration is at its most efficient, they grow artisanal ice crystals in order to create machines which simply return to water when their makers tire of them. They electrolyse metals from sea water and lay down skeins of gold within the shifting interstices of icebergs. Ice becomes the key to their technology. Evolved from cold-blooded stock, they are nonetheless still adapted for cold-water living. Their blood is laced with antifreeze; their metabolisms burn fiercely to maintain the energetic demands of their busy minds.