Chlorine is a greenish gas (at room temperature) that is highly toxic; in fact, it was used as one of the first chemical weapons in modern times by the Germans in World War I (The War That Didn't End All Wars). Sodium is a grey/silver metal that burns on contact with air and will explode on contact with water; it has been used for centuries in sea to sea battles. Lovely stuff, each of them on their own. Combine them, though, and you get ordinary table salt; quite tame and even tasty. (Hang on... salt is linked to hypertension, aka the silent killer; so I guess they didn't completely change their spots, just went from violent to subversive.)
When I still had children around the Shabbos table, we would learn some simple halachos of Shabbos each week at the s'uda (usually the evening s'uda, sometimes lunch also). When we finished Shmiras Shabbos k'Hilchaso, we worked on Muktza. You may be thinking, "aargh... that sounds so dreary." Maybe so. And how do corpses sound to you? You probably never had a corpse at your Shabbos s'uda, but you can imagine it would be quite a mood killer. Yet, you put these to things together and you get quite more fun than a barrel of monkeys (also muktzah, btw).
The fun started when we started discussing what to do if a fire breaks on Shabbos and you have a corpse in your dining room. "Of course," I said, "you are going to want to get that corpse out of harm's way." "Of course," said my wife somewhat sardonically. "And also of course," I continued undaunted, "the corpse is muktza." Having not given a lot of thought to what the status of corpse in her dining room might be, my wife didn't have an answer for that. "So... Chazal decreed that you could move the corpse by putting a baby or loaf of bread on it." Ok; this is really when the fun started. "There is no way I am putting my baby on a corpse!"
The point is that a corpse is the worst kind of muktza. It can't be used for anything, so it is "muktzah machmas gufo" -- inherently muktzah and therefore cannot be moved even if you need its place (for example, you want to invite in some cohanim) or some permitted usage (I can't think of an example; except possibly "scare crow", and that is forbidden because of kavod ha'meis). So you are really stuck. So Chazal, who created muktza in the first place, also created the escape hatch of "kikar o tinok"/bread or baby as a special heter because of kavod ha'brios (human dignity). The way that works is that corpse (for which you have no particular use) is elevated to be a support for the baby (or bread). Since the baby can be moved, the corpse is supporting it, and right now are more interested in the baby (or bread), they can both be moved together.
This only solves the muktzah problem, of course. If you want to move corpse into a r'shus harabim (or even a karmelis), then you are really better off using a baby who can crawl than bread or a newborn. That is because carrying a person who can move himself is only assur m'd'rabanan. See? The topic opens up all sorts of dicussions -- tiltul min ha'tzad (indirect movement), chai nosein es atzmo (a person carries himself), bahsis l'davar heter v'davar assur (support for two items, one of which is muktzah, but the other is not), etc, etc, etc. The fun just never stops. For more details see Shulchan Aruch, OC 311.
My wife still said to me, however, "The only way my baby is going on a corpse is over your dead body!" I said, "Honey, the expression goes 'Over my...." Oh... wait... ah... I get it now.