Telkhine



  Telekhines (or Telchines or Telkhines''') were mysterious magician-smiths and sea demons native to the islands of Keos and Rhodes. They were the children of Thalassa and Pontus.'''

History
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". this is a bullshit answer