It now has a painted crucifix after the late medieval Mediterranean style. Done by a Benedictine artist and featuring the two patron saints of the two Dominican provinces who have their young friars study at this house: the German philosopher/scientist bishop St Albert the Great and the Peruvian mulatto doorkeeper/local healer St Martin de Porres.
I wouldn't be surprised if the Cross with vine/tree of life motif was inspired by the apse crucifix at San Clemente in Rome, which the Irish Dominicans have had charge of since 1667, when the Brits expelled them from their homeland.
Who the tiny guys are down below, I know not. Suspicions: the monk hiding on the left might be the painter. The guy kneeling at the bottom might be the donor.
The scroll contains the opening words from the sixth-century hymn to the Cross Crux fidelis by Venantius Fortunatus, who eventually became bishop of Poitiers: Faithful Cross, O beauteous Tree, peerless and divine.
Friars chanting the Office.