The question is not 'what is consciousness?' but 'what is not-consciousness?', that is, what is its negation or negative? Naturally we think that the answer is inanimate stuff, dead matter, or 'rocks and stones and trees', but these of course are objects in consciousness, as is every other conceivable negative. Or you could frame it as 'what is the nothing behind consciousness, out of which it emerges and into which it returns'? The answer must go deeper that all worlds, living or dead.