Spider Sailors of the Super-Sargasso!

Artisanally-crafted fantasy worlds are often filled with logical concepts taken to their completely illogical conclusions. So here's a very stupid concept that might have to become A Thing™.

Winds and electric fields potentially blow anything sufficiently small into the upper atmosphere — viruses, bacteria, insects, whatever. (A lot of snow crystals form around plant viroids, for example.) There's a constant, dusty stream of life floating above our heads. Scientists call this "aeroplankton," and it's rad. Spiders do it all the time.

When the aeroplankton topic was mentioned the other day, it sparked the realization that fantasy worlds are replete with weird diseases and giant spiders. You can probably see where I'm going with this.

Imagine a layer of the atmosphere teeming with flying oozes blown thin and floating like weather balloons. Parachuting spiders, parasailing across the sky, occasionally landing on the decks of airships or raining down on unsuspecting towns. ("The farmers' alamanc says to stay in doors today, giant spider migration is supposed to hit. Lock your barns, or else they'll eat all the sheep.") Everything's fine one minute, then your town suddenly gets hit with mummy rot that's been floating in the upper atmosphere from that adventuring crew that blew up that tomb a few weeks ago.

In theory, only low-weight things can be blown about by this method, but fantasy worlds are dumb and filled with contradictions. Maybe giant spiders can ride the magnetic fields with their strange, magic webs. Slimes grow thin, blowing away like paper on the wind as part of their mass-migration strategy. Treants sporulate, their consciousness blowing away in the wind until they root and grow elsewhere. (The odds of some complicated magical life cycles emerging from this behavior are high. Cast purify food and drink in the right spot, and you suddenly have something a century old and 5,000 miles distant growing there. If you think aeroplankton and fire ecology are complicated, what happens when you add gods and magic and ancient conspiracies to the mix?)

Even if you find megafauna skating across the sky stretches credulity, you can still get somewhere with strange spores, eldritch diseases, and tiny animals being randomly blown into your town. One day, your town is normal. The next? You suddenly have a fungoid incursion, and now the political situation is significantly different.

Aeroplankton: add them to your random encounter chart today!