Slightly related:

Aliens in our midst

In fact, they were profoundly different from any other animal on Earth.
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The ctenophore was already known for having a relatively advanced nervous system; but these first experiments by Moroz showed that its nerves were constructed from a different set of molecular building blocks – different from any other animal – using ‘a different chemical language’, says Moroz: these animals are ‘aliens of the sea’.
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Once you repeat the experiments, says Moroz: ‘You start to realise it’s a really different animal.’ He surmised that the ctenophore was not just different from its supposed sister group, the jellyfish. It was also vastly different from any other nervous system on Earth.
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It meant that the nervous system of the ctenophore had evolved from the ground up, using a different set of molecules and genes than any other animal known on Earth. It was a classic case of convergence: the lineage of ctenophores had evolved a nervous system using whatever genetic starting materials were available. In a sense, it was an alien nervous system – evolved separately from the rest of the animal kingdom.
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The ctenophore represented the closest thing to an alien brain, or mind, on Earth