Romulan Biology

The Romulans began as a revolutionary group of Vulcans who were referenced as "those who march beneath the Raptor's wings" and refused to accept the Vulcan philosopher Surak's teachings of complete suppression of emotions. Around 400 AD, the dissident group split off from Vulcan society and began the long journey to the planets Romulus and Remus.
The Romulans are of the Vulcan species. One of three theories regarding how the Romulans arrived at the stellar system that includes the planets Romulus and Remus involves Sargon's people.
Romulans have pointed ears, upswept eyebrows, and copper-based blood that is green when oxygenated in the arteries and copper or rust colored when deoxygenated in the veins. The Romulan heart is said to be gray, though this may simply be poetic imagery. Many Romulans have a V-shaped ridge above the bridge of their nose but not all do, Like Vulcans, When in mourning Romulans in an effort not to forget the loss of their loved ones, tattooed the designs on their faces rather than using ink (which wears off in time, signifying an end to the mourning period) showing that they would forever mourn.