There is another Earthworm in Kelan North Woods. It's level 4, has 60 HP, and it is earth element. I'm afraid I don't know how to check the rest of his stats, so I added him to the database only with those stats I know about.
The Earthworm can be found right before the passage from first to second part of the woods.
Having a signature is like keeping a gremlin.
Just don't overfeed it, don't make it wishy-washy and you'll be a good responsible Signature Keeper :]