The third (non-male, non-female) sex of the Oankali in Octavia Butler's Xenogenesis trilogy. The ooloi are powerful natural genetic engineers. They have three phases of life: unsexed children (which stage all Oankali pass through), then after a first metamorphosis, ooloi child (definitely an ooloi, but not sexually mature. able to effect genetic changes, but not to give pleasure in doing so.), and after a final metamorphosis in which the distinctive extra pair of arms is grown, adult ooloi. Ooloi secrete a drug-like scent which they can control to be very attractive to potential mates, or calming, or any of a host of things. They are called seductive because of this ability to manipulate emotions.