The "Huolongjing" also describes and illustrates the oldest known multistage rocket; this was the "fire-dragon issuing from the water" (huo long chu shui), which was known to be used by the Chinese navy. It was a two-stage rocket that had carrier or booster rockets that would automatically ignite a number of smaller rocket arrows that were shot out of the front end of the missile, which was shaped like a dragon's head with an open mouth, before eventually burning out. This multistage rocket is considered by some historians to be the ancestor of modern cluster munitions. Needham says that the written material and illustration of this rocket come from the oldest stratum of the "Huolongjing", which can be dated to about 1300-1350 from the book's part 1, chapter 3, page 23.