While it's clear that slime molds can learn and make decisions, and that these attributes are fundamental features of consciousness, it's hard to understand consciousness in single celled creatures. As you note, they don't have brains at all.

Which leads to the conclusion that consciousness doesn't arise in the brain.

Wew lad! But, once you grasp that fact, the floodgates are open, and all our assumptions about consciousness can fall away so we can start building an understanding based on what we can actually confirm. Or, well, at least on what we haven't falsified. Yet.

For instance, while brains react to electrical signals, and emit them, consciousness isn't electricity. If it was, we'd be able to map it out, and have a lot more metrics by which to figure out what it's doing, what it is, and where it comes from, but despite Kirlian photography claiming to be of auras, which are claimed to be our spirits, souls, or consciousness, that's just not true, because we can make those auras and manipulate them with electricity in various ways that don't create consciousness or affect it in living conscious creatures.

So, it isn't electricity. Another thing is that we have no way of determining consciousness isn't something inanimate objects, like rocks, have. It's not electricity and we don't know what it is, so we have no way to test for it in rocks. We can't observe rocks make decisions, because they can't move, but I can't move when I'm anesthetized either, so that's not a defining feature of consciousness.

This brings me to the last point I want to make here, which is that we clearly exercise our conscious minds when we're asleep, or in comas, or anesthetized, states we define as unconsciousness. We understand consciousness so poorly it's the best word we have for it, and it's antithesis, or opposite, is a state we need to include in it.

Basically, we just have no idea where consciousness comes from, what it is, or why.

Cool videos about mushrooms too.

Thanks!