This is such a mistake, but My Singing Monsters is doing that on purpose...

Shrubb has two elements so it should be worth more diamonds than other one elemented monsters. So, this is My Singing Monsters's mistake in the game.

But, this is not true! Actually I would like to say that, but yes, it is true because Shrubb has very low popularity than other one elemented monsters. Not actually, vice versa. The Monster-Handlers also thinks vice versa... So this is their mistake.

purpose...