First one lensing Necromonger and then a second appeared, followed by a specialist squad of soldiers. The lensors were troops who had lost their faces, or parts thereof, in battle, but who through the application of modern military medical technology remained —salvageable. Eyes and ears gone, mouths replaced with injectors, even noses blasted away, they had been converted into biological tracking devices whose melding of human biologics and electronic enhancements could not be equaled by equivalents that were either purely organic or wholly mechanical. Eerily silent, they led the way along the thoroughfare, single-mindedly searching for survivors. In ancient times, humans had used specially trained dogs for such purposes.
-The Chronicles of Riddick (page 90)

	There was another lensor. Trailing the squad, it hesitated. Perhaps Laijun breathed too strongly and it detected the sudden rise in carbon dioxide. Possibly Ziza inhaled too sharply and the working of her small lungs was overheard. Or it might have been the pounding of Imam’s heart. Whatever the reason, the creature turned.
-The Chronicles of Riddick (page 92)