Exodus

Earth was attacked by some unknown nano life form. This invisible menace digests flesh and metal, causing panic in the population. A putrid, but somehow sweet, smell infested the cities, spreading from the rivers first, then the culverts. The rich people didn´t even care until all their water taps start to drip this acid like fluid.
Oddly, in the sea some species of fishes wasn´t totally decomposing. After some bioengeneering research, the leading cientists breed a headless living fish with a carbon fiber exoeskeleton, large enough to carry millions of humans in its endoderm.

Now the captains of this huge beasts carries an entire race, without a destination, visiting planets that could mantain human life. However, their peaceful and unending quest urges: the cryogenic sleep proved useless, as some of the settlers awoke with brain damage.

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