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However, when comparing being whacked in the head with a helium filled balloon, versus a water filled balloon, the effect can be quite perceptible ... :) ...

No ... the ratio of an object's weight in air, versus in water, on the earth's surface near sea level, varies dramatically with the density of the object.

Gold has a density 19 times water, so...

Perhaps not now, but perhaps there was such a museum back in the 1880's, when this horned skull was reportedly found in Pennsylvania ?

Perhaps this is because the earth was smaller then, so had less gravity, allowing more massive animals to move about easily. Some of the bigger dinosaurs would not be able to stand up and hold their...