Blindsense

Shirrens’ sensitive antennae grant them blindsense (vibration)—the ability to sense vibrations in the air—out to 30 feet. A shirren ignores the Stealth bonuses from any form of visual camouflage, invisibility, and the like when attempting a Perception check opposed by a creature’s Stealth check. Even on a successful Perception check, any foe that can’t be seen still has total concealment (50% miss chance) against a shirren, and the shirren still has the normal miss chance when attacking foes that have concealment. A shirren is still flat- footed against attacks from creatures it can’t see.