mereterminid
A mereterminid is a speculative organism that combines characteristics of a mermaid and a teredinid, commonly known as a shipworm. Shipworms are marine bivalve mollusks that bore into wood. A mereterminid, therefore, would be a creature with a serpentine, fish-like lower body, similar to a mermaid, but with the ability to burrow into and consume wooden structures.
The hypothetical anatomy of a mereterminid would likely include a muscular tail for propulsion and maneuvering,
The ecological role of mereterminids, if they existed, would be significant. They could act as important decomposers