Mario_4_Life

You need to go back to that place with the golem (which can't get upgraded by the way) and go the room after you fight the two lizard thingys which got unlocked. From there, there should be to your right a gap which is impossible to jump over unless you have the grapple swing upgrade. To the left you should see a morph ball wall, or to be specific, a wall which you could enter as a morphball. Go back and look around with your scanner until you find something that can be broken by a morphball bomb. Find it, destroy it, then go in, and off you go.

Also, there is a missle expansion there, only gettable by attaching yourself with the bugs near you as a morphball (the ones that never seem to stop showing up after killing all of them). Once you have enough, you should be floating upwards. Head to the left, as there is a creature who will damage you if you go into it floating. Once near it, place a bomb and then it's yours.