// ImmovableBlock's can not be destroyed. If a projectile collides with one, the projectile is removed.
if (obs instanceof ImmovableBlock) {
ImmovableBlock c = (ImmovableBlock) obs;
if (c.getRectangle().intersects(p.getRectangle())) {
p.collided();
projectileList.remove(p);
c.recieveDamage(p.getDamage());
notifyObservers(new Point(p.getLocation().row - 12, p.getLocation().col - 12));
setChanged();
break;