It is a shield. The Latin word is scutum and comes from prior to the empire. Prior to and after the Empire the shields tended to be oval or round. During most of the empirical period they were rectangular.
Excellent images can be seen of both styles by searching for "scutum (shield)" on wikipedia.
it is a weapon used by poseidon
The Roman Army about 200 BC.
Roman engineering did not have any secret weapons. None of the Roman engineering achievements were kept secret.
Roman
The dome on a Roman shield is called a boss and it was used in an offensive action. A shield, although its prime purpose was defensive, was also used as an offensive weapon in a pushing movement.
The pincipal weapon of the Roman cavalry was a sword called spatha.
a pike, which is a spear like weapon
yes
A thunderbolt.
The roman army did not use nuclear weapons.
The "Short Sword" was the standard Roman Infantrymen's weapon.
Jupiter was the Roman god associated with thunderbolts. He was the king of the gods and the god of the sky and thunder, similar to the Greek god Zeus.
a mirror
it is a weapon used by poseidon
They used swords and spears
The 'boss' or 'umbo' in the center of the Roman scutum was used as an auxiliary punching weapon.
The Roman Army about 200 BC.