For 10 points, identify this object prominent in the story of the Seven Against Thebes which was fashioned by Hephaestus for the wife of Cadmus.
The presence of the owner of this object in the region of Psophis prevented crops from growing, and this object was dedicated at Delphi by Acarnan and Amphoterus. Following the matricide of (*) Alcmaeon, he was purified by Phegeus and married his daughter Arsinoe, giving his this object. Polynieces used this object to bribe Eriphyle to make her husband Amphiaraus go to war. For 10 points, identify this object prominent in the story of the Seven Against Thebes which was fashioned by Hephaestus for the wife of Cadmus.
The presence of the owner of this object in the region of Psophis prevented crops from growing, and this object was dedicated at Delphi by Acarnan and Amphoterus.
Necklace of Harmonia