Justine and Manjuele wore masks made from the bat-like skulls of Time Lords from a history where they lost their war against the Great Vampires. (PROSE: Alien Bodies) These masks resembled Mal'akh skulls. (PROSE: The Book of the War)
Francesca wore a mask made of synthetic bone.
In the late 18th century, one mask fell into the hands of the Service, who kept it in their private collection. The Royal Society frequently requested they be allowed to scientifically examine the mask, but they never got a chance to do before it was lost at the turn of the 19th century. (COMIC: Political Animals)