They invented the art of metal-working and were said to have crafted the sickle Kronos used to castrate his father Uranus and later a magical trident for Poseidon which the god used to level mountains into the sea and form the islands. Their malignant use of magic later angered Zeus, who cast them beneath the sea or into the very depths of Tartarus. Telkhines were sometimes described with the heads of dogs and fish-flippers for hands. They are also known as "fish children".
Telekhines have faces like dogs, with black snouts, brown eyes and pointy ears. Their bodies are sleek and black like seals. They have stubby legs that were half flippers and half foot, and humanlike hands with sharp claws. Percy described that if you blended together a Dobermann pinscher, a child and a sea lion, they'll look a bit like a Telekhine. Fully grown adults can be up to two and a half metres tall. Telekhines bark and growl, and they waddle instead of walking.