But as long as you can literally list, and it could be an infinite list, but if you could list the values that it could take on, then you're dealing with a discrete random variable. Notice, in this scenario with the zoo, you could not list all of the possible masses. You could not even count them. You might attempt to, and it's a fun exercise to try at least once, to try to list all of the values this might take on. You might say, okay, maybe you could take on 0.01 and maybe 0.02. But wait, you just skipped an infinite number of values that it could take on because it could have taken on 0.011, 0.012. Even between those, there's an infinite number of values it could take on.