I noticed there weren't any entries in the system for False Hydras, so I went searching for some homebrew materials.

The concept without stats can be found at goblinpunch.blogspot.com.

The status blocks I used are found at homebrewery.naturalcrit.com. This also gives greater detail to the backstory and usage of these creatures in a game.
I made some minor modifications and included extra abilities to pay tribute to the commonly associated Legend of Zelda OoT monster, Dead Hand (marked with *).
Please be aware, using these extra abilities increases the Challenge Rating of the monster as it now has ways to grapple multiple creatures from a greater distance with relatively high escape DCs.

This file includes the five stages of growth that a False Hydra goes through: Larva, Pupa, Young, Standard, and Elder.