This sculpture, along with two more groups (one of Heracles fighting the sea-god Triton, and one of lions devouring a bull), was part of the decoration of one of the two pediments of the Hekatompedon, most likely the western one, and was created around 570 BC, during the early Archaic period.

[5] The item is made of a sort of porous limestone (porolithus), and measures 3,35 m. in length and 79 cm in height.

The two large and shallow round cavities that make up his eyes are red, with light green irises.

The second boy's skin is likewise reddish, with colour remaining on the chest and left halve of the face.

The serpentine form's tail show a red band running along the length of it between two black-blue ones, with one in the natural color of the stone.

To fix them, holes (as seen in the arm and shoulders of the monster) were made, 6-7 millimeters wide, in order to preserve the lead.

It has been suggested that it could be the shapeshifting sea-god Nereus, or the serpentine monster Typhon, who once attacked the Olympians.