What it is like? So you are comparing one entity experiencing something to another. Experiencing is a process that takes place inside the entity and among its component parts.
Know you are that thing - every thing is itself, if it has well defined boundaries. Knowing something is just having access to that information and good reasons to believe it to be correct. Here we have a tautology - that a thing is itself - so it doesn't require much to know that. What you are probably more interested in is a mechanism that can take advantge of that knowledge in various ways. Like self preservation.
Humans are self conscious.
Crabs are self conscious too because they act with a purpose of self preservation, which requires knowledge of what is them and what is not them.
Crystals do not have this knowledge or do not have a mechanism to act on it in a way that manipulates semantic symbols.