Yorik Coral
this form of coral was found in the galaxy inhabited by the Yuuzhan Vong. They bio-engineered the coral to grow to massive sizes, and then formed it into living spaceships they called worldships. The worldships themselves resembled nothing more than asteroids when observed on standard scanners and sensors, allowing the Yuuzhan Vong to enter an area virtually undetected. When the Praetorite Vong invaded the galaxy, they had planned to use the dead world of Belkadan as a yorik coral breeding ground. The New Republic discovered that the Yuuzhan Vong captured slaves and used them to breed the coral. Small buds of coral were carried to captive slaves by creepers, which inserted the young buds into the slave's flesh. The coral - known as yorik-kul - kept the slave from revolting while it drew nourishment from the bodily fluids and energy of the host. It was later learned that the yorik coral used to create the Yuuzhan Vong starships aged like most other biological organism. By the time some of them reached the known galaxy, their interior components had begun to simply die out. Bioluminescent polyps stopped providing light, and organisms created to regulate temperature were unable to continue.