@Model
	private void setActiveWorm(Worm worm) throws IllegalArgumentException {
		if (worm == null)
			throw new IllegalArgumentException("The worm isn't allowed to be a null reference.");
		if (!worm.isAlive() || worm.getWorld() != this)
			throw new IllegalArgumentException("The worm provided as active worm must be alive and in this world.");
		this.activeWorm = worm;
	}