Transcription factors (genes whose products modulate the activity of other genes) in the nucleus of each cell form regulation networks that are isomorphic to ne

Transcription factors (genes whose products modulate the activity of other genes) in the nucleus of each cell form regulation networks that are isomorphic to neural nets (with targeted activation/inhibition). Some unicellular life form even have an eye-like organelle, with substructures analogous to our lenses, corneas, irises, and retinas. https://en.wikipedia.org/wiki/Ocelloid https://en.wikipedia.org/wiki/Ocelloid There's also evidence for a distributed decision process to open and close the stomata on the surface of plant leafs in an optimal way. https://www.pnas.org/content/101/4/918 https://www.pnas.org/content/101/4/918 So an absence of nervous system doesn't necessarily entails a lack of complex information processing. Whether that information processing underlies some kind of conscious experience, and assuming it does, whether such experience is anything like ours is an open question. Once you reject solipsism, it is hard to put a logical limit to what can or can't be conscious.