Tritons

Triton, a mythological sea creature, is identified as the son of Poseidon, god of the sea, and the nereid Amphitrite. One attribute of Triton was a great shell that, when played like a horn, had the power to calm storms. Triton was usually depicted as an ichthyocentaur, with the upper half human and the lower half in the shape of a fish tail.
In classical representations the name triton or merman was given to all minor mythological sea creatures that formed the procession of Poseidon, considered Triton’s sons.