Search and Mark

Search and Mark is a companion perk in Fallout: New Vegas gained while Rex is a companion.

Effects
This perk highlights food, chems, firearms, and ammunition within a short distance in a green outline while zooming in unarmed or aiming down a weapon's sights.

Containers (i.e. Refrigerator, metal box, etc - including corpses and hollowed-out rocks) that have one or more of these items inside will also be highlighted. Once the items are removed, the container will no longer be highlighted.

Bugs
Some killed creatures such as lakelurks will be highlighted despite their bodies not containing anything they can be looted of. In the case of lakelurks this may be due to their shriek "weapon" they carry, which is classified as a weapon with ammunition but cannot actually be obtained.