Seahorses lead quiet lives, tucked away out of sight on the seafloor. It is rare to catch a glimpse of a seahorse in its natural habitat. But even if few have seen one live, these exotic, seemingly prehistoric creatures exist quite vividly in our imaginations and they have mesmerized scientists, artists, and storytellers throughout time with their otherworldly rarity. Poseidon's Steed is a sweeping journey that takes us from the coral reefs and seagrass meadows of Indonesia where many seahorses makes their natural habitat to the back streets of Hong Kong where a thriving black market seahorse trade is concealed. Throughout history, seahorses have surfaced in some unexpected places and Scales also follows the seahorse back in time, from our most rudimentary seahorse imaginings six thousand years ago on cave walls in Australia, to the myths of ancient Greece. Scientists have long puzzled over seahorses' unusual anatomy and their very strange sex lives. And male seahorses are the only males in the animal world that experience childbirth! Seahorses are not what scientists call a "keystone" species. They rely on a healthy ocean to survive, but the marine ecosystem does not rely on them. But their delicate beauty reminds us that we rely on the seas not only to fill our dinner plates, but also to feed our imaginations.