The Kera-boa was a gelatinous organism which was used by Yuuzhan Vong Shapers to cover the frame of a growing Vangaak.
Once attached to the vangaak frame, the kera-boa would reproduce rapidly, creating a semi-sentient protoplasmic colony which sprouted millions of long, microscopic tendrils that dangled below the craft. These tendrils were made to move together and could propel the craft in any direction.