Highbreed Tree Monster

The Highbreed Tree Monster was a fail safe that would be activated if the Highbreed lost the war on Earth. It was accidentally activated by an earthquake. It only appeared in If All Else Fails.

Appearance
The failsafe looks like a giant Highbreed covered in plants and other organic matter, and since Ben was trying to go Way Big to stop it, Ben thinks that it is about the size of Way Big. However, even as Ben became Humongousar (full size at 60 ft), he didn't even reach the creature's "knee cap". Way Big being about 3 times taller and would only rise up to about the creature's "waist". Since the waist of a human is about halfway up one, if this is the same with the Rock Monster, since Way Big is about 200 feet tall (if his height hadn't change throughout the series) then the Highbreed Tree Monster is about 400 feet. The inside is simmilar to a human immune system.

Weaknesses
It apparently had no weaknesses as it was designed to be an unstoppable doomsday weapon due to both its size and power. It was only brought down when all of its controls were overridden.

It might also be damaged if it falls, due to its size.

Trivia

 * It's currently the largest of Ben's enemies, being even larger than Way Big (possibly twice his size), Ben's biggest alien.
 * So far, it's the only one of Ben's enemies to bigger than Way Big.