A grown slow returner is as long as a tall man lying down, its shell a broad, smooth, heart-shaped dome of olive-brown plates, each plate rayed with darker streaks, often grown over with weed and barnacles. Its head is blunt, scaled, and beaked, with large dark eyes, and its front flippers are long and wing-like; underwater it seems to fly, beating them slowly. Ashore it is heavy and slow, dragging itself up the sand with both front flippers at once and leaving a broad, ridged track. A nesting female breathes in long, groaning sighs, and her eyes stream with clear tears that wash away the sand and salt.

They live in the open sea and along the outer water of the Tidebound Reaches, grazing the kelp and sea-grass of the shoal worlds and the reefs, and they travel very far. They nest on a few sandy beaches of the outer isles of the Tidelace and the island margins of the Reaches.

They graze on sea-grass and weed and eat jellyfish, including fogbells, and crabs and shellfish. They are solitary, slow, and calm, indifferent to swimmers, and allow the Thaluren to swim beside them.

Every few years a female swims back to her natal beach, from whatever water she has been in, and in summer nights comes ashore several times to dig a deep pit above the tide line and lay a hundred soft white eggs in it. She covers them and returns to the sea. Weeks later the hatchlings dig out together at night and run for the water, and birds, crabs, and fish take most of them on the way. Those that reach the sea are not seen again until they are grown. Slow returners live as long as a Human, perhaps longer, and take decades to come of age.

They harm no one. Gnome harbours on the outer isles mark their nesting beaches and keep people and dogs off them in summer, out of old courtesy to their Thaluren neighbours, and to keep the peace with them. Some coastal Humans take their eggs, which the Thaluren regard as a wrong done to a clutch.

In Thaluren belief the slow returners are lesser kin in the rule of return: they hatch in a known place, go out, and come home to it to lay, and so their clutches are owed the protection owed to any clutch laid in its own water. A Thaluren who kills one, or who takes its eggs, is held to have harmed a return and is shunned by the runs. Outside Thaluren water it is only belief, and other peoples keep it or not; a Human egg-taker on a far beach answers to no one. The Thaluren say a returner swimming alongside a run is a good omen, and that a beach the returners stop coming to has gone wrong, as the First Nesting Confluence went wrong.