They were descended from an arachnid-like creature and were tall and spindly looking. They had two pairs of black eyes and short purplish fur-like hair that covered their entire body. They had three fingers on each hand and long arms that made them excellent climbers.
M'rok culture was known for its honour duels. Any M'rok had the right to challenge another if they took offense to a statement or action by the other party. One of the traditional weapons they used for the duels was known as the ta'tak. Due to the subjectiveness of what one could consider an "offense" the M'rok had elaborate customs of courtesy and tactfulness, which made interactions between and with them a lengthy process due to their roundabout, but polite, ways.
In 2366, the M'rok entered into an alliance with the Romulan Star Empire. They have since adopted many items of Romulan culture with Romulan aesthetics becoming a fad during the late 2360s and 2370s. (Ship Recognition Manual, Volume 5: Starships of the Romulan Star Empire)