On the reverse of this fine coin we can see the Dioscuri, Castor and Pollux, stood side-by-side with their horses. They were the sons of Zeus, and came to be immortalised through a tragic story. The ‘Heavenly twins’ were inseparable from birth, Castor becoming renowned for his skill at horsemanship (though both brothers rode swift white horses), whilst Pollux excelled at boxing. They lived the normal life of any great hero of their time, voyaging with the Argonauts and taking part in the Calydonian boarhunt (depicted on the silver denarius recently added to my collection). The trouble for the Dioscuri began when they got into a quarrel with their cousins Idas and Lynkeus. There are a couple of differing explanations for the fallout; one involving girls and the other involving cattle! In a confrontation with the cousins Castor was mortally wounded by Idas, whereas Pollux had the benefit of being immortal and so safe from injury. Pollux avenged his brother by killing Lynkeus with his spear, whilst Zeus hurled a thunderbolt at Idas (thanks dad!) With both cousins dead, Pollux returned to Castor, who was now at the point of death. Weeping, Pollux begged Zeus to allow him to die with his brother, so the god offered him a choice. Either Castor went to Hades while he himself took his place among the gods on Olympos, or Castor could share his immortality, with the caveat that the brothers spent alternate days in the Underworld, and the other days on Olympos with the gods. Pollux chose the latter without hesitation, and Zeus immortalised the brothers in the stars as the constellation Gemini, the Twins, to commemorate their mutual devotion. The Dioscuri were important to the Romans, since they fought with them in a great battle against the Latins in 499 (or 496) BC. As soon as the battle was over they appeared in the Forum at Rome, their horses bathed in sweat, and announced the resounding victory. The temple of Castor was erected nearby to commemorate this event, three columns of which still stand today. The Dioscuri were the protectors of travellers, particularly sailors, and so it is no coincidence that this coin was minted in Ostia, an important harbour city of ancient Rome.

MOSTP=Moneta (money) from the first officina in Ostia

The fact that the flan is enormous and the coin has been struck perfectly centered with the full detail including the dotted border on both sides, leads me to believe it's a trial strike of some sort.

MOSTS

"Ostia" (plur. of "ostium") is a derivation of "os", the Latin word for "mouth". At the mouth of the River Tiber, Ostia was Rome's seaport. Ostia housed a late imperial mint; this coin of Maxentius was struck there. On the reverse of this fine coin we can see the Dioscuri, Castor and Pollux, stood side-by-side with their horses. They were the sons of Zeus, and came to be immortalised through a tragic story. The ‘Heavenly twins’ were inseparable from birth, Castor becoming renowned for his skill at horsemanship (though both brothers rode swift white horses), whilst Pollux excelled at boxing. They lived the normal life of any great hero of their time, voyaging with the Argonauts and taking part in the Calydonian boarhunt.