The Kalishari are a race of humanoids native to the windy planet Kalisha, near the Union of Ergath. They have long non-prehensile tails and color-changing skin. However, this color change works pretty badly as camouflage, as the changes are linked to their emotions. Happiness is bright green, anger is red, fear is deep purple, and neutrality is blue.

Of course, this pales in comparison to the Kalishari's internal abilities. In an instant, a Kalishari can inflate their torso into a six-foot-wide sphere full of biohelium.

What's biohelium, you ask? It's just helium, but it's produced by living things (through magic), and it changes density when electricity is applied to it (again, through magic).

Anyway, the Kalishari achieve their inflation in a pretty remarkable way.

1. They have a special membrane (called a wisedimod) between their ribcage (which is made of hexagonal plates of bone connected by ligaments) and their internal organs.

2. They have a bunch of extra tendons connecting all their internal organs to the membrane to hold their organs in place.

3. They have a special gland (called a wisòya) that can produce biohelium.

4. Their skin is very stretchy and can withstand being stretched into a smooth sphere (save for the arms, legs, and tail, which simply dangle from the torso, much like a jellyfish's arms.

5. Through the application of electrical brain signals, they can change the density of the biohelium.

And that's how a Kalishari can float like a balloon, bounce like a rubber ball, or crush things like a wrecking ball.

This inflation mechanism evolved as a combination self-defense and escape mechanism. The animal the Kalishari evolved from either scared off predators through increased size, or was able to float to safety on one of Kalisha's strong winds. And even if they did get attacked, their stretched-out skin would simply be punctured, causing them to zoom around haphazardly, as their musculature is strong enough to hold them together.

Today, the Kalishari inflationary system serves little purpose other than as a way to fly to places at ~60 mph. However, its survivalist purpose can sometimes show through, specifically when strong emotions, such as anger or fear, activate the Kalishari fight-or-flight response, which invariably causes inflation.

However, like anything a sapient species evolves, inflating can have its downsides. For example, Kalishari space travelers and mountain climbers have to take into account the local air pressure of their destination, so as to not experience full-body bends.

Intoxicants such as ethanol can also cause involuntary inflation by redirecting brain signals to the wisòya. This reaction is affectionately nicknamed "party ballooning".