Signum/Manus
The signum(sign) consisted of a bunch of philarae(disks/medalions) on a long pole with a manus(type of signum) or leaf-shaped spear at the top. There were 1-6 philarae on each pole and the number of philarae is thought to represent the number of the century within a legion because there are 6 centuries in a legion and no more than 6 philarae have ever been found on a signum. The signum was the standard for the centuria and the manus symbolized an open palm and the oath of loyalty that the soldiers took. The signifier carried the signum for a cohort or century. This was a very dangerous job because the signifier had to stand in the very front of the rank and his only protection was a buckler(small circular shield). The maniple formation, made of two groups of 80+ soldiers each, was used for two centuries during the Roman Republic. In the first century, the manus sat at the top of the philarae, but in the second century, the spear topped the philarae. The signum is widely known as an ancient roman icon, perhaps even more so than the aquila.