The clouds
are made of a strange anti-gravity material that draws power from the Mushroom
Zone light source (no one knows where that comes from, either). You
can indeed stand on them, and many mushroom buildings are built on top
of them, including at least one Mushroom Portal. Clouds easily absorb
energy, and will eventually explode if overloaded (with energy). This happens
when they are shot with any humans or mushroom energy weapon (desint-o-ray,
anti-human ray, etc.) They can also dispense small amounts of energy as
lightning. The clouds rain down Cream of Mushroom Soup that evaporated
from the ocean. Most humans trying to get into The Mushroom Zone die here
trying to get to the surface.