Usually when we say "consciousness", we mean self-awareness. It's a phenomenon of our cognition that we can't explain yet, we believe it does causal work, and if it's identical with self-awareness, it might be why we're having this conversation.

I personally don't think it has much to do with moral worth, actually. It's very warm-and-fuzzy to say we ought to place moral value on all conscious creatures, but I actually believe that a proper solution to ethics is going to dissolve the concept of "moral worth" into some components like (blatantly making names up here) "decision-theoretic empathy" (agents and instances where it's rational for me to acausally cooperate), "altruism" (using my models of others' values as a direct component of my own values, often derived from actual psychological empathy), and even "love" (outright personal attachment to another agent for my own reasons -- and we'd usually say love should imply altruism).

So we might want to be altruistic towards chickens, but I personally don't think chickens possess some magical valence that stops them from being "made of atoms I can use for something else", other than the general fact that I feel some very low level of altruism and empathy towards chickens. Or, to argue Timelessly, we might say that I ought to operate with some level of altruism for the general class of minds like mine, which includes most Earth-based animals, since the foundations of our cognitive architectures evolved very, very slowly (and often in parallel shapes, under similar selection pressures); certainly I personally generally feel a moral impulse to leave Nature alone, since I cannot treat with most of it as one equal being to another.

Consciousness definitely exists, but I think it's worth not treating it as magic.