Sheilei are shimmering, serpentine creatures with translucent golden scales, measuring more than nine feet in length. Its tail fin nearly doubles the length, however, lashing back and forth like a cat's tail. A pair of broad, flat pectoral fins extend outward like aqueous wings, delicate in appearance yet powerful enough to propel the creature out of the water. The most striking feature of the monster, however, is its broad jaw and enormous mouth, filled with three rows of razor-sharp teeth that curve and twist, locking together like a tangle of briars.