Ambles

Ambles is a sentient tree monster found as an easter egg if one digs with a spade fifteen blocks north of Falador's north gate. Upon digging in this spot, Ambles will appear and yell 'Oh, not again!' before attacking the player, stunning them, and despawning.

Trivia

 * Guards will occasionally mention a 'grumpy old tree-thing' when you talk to them in Falador. Apparently, they occasionally dig him up for fun.