"Ossuary" sounded like the right word for "bone box," but the context in which I'd heard the idea was an old Jewish custom of reusing tombs. You'd put somebody in there, wait for a couple years until they were just bones, gather the bones in a box (which was what I thought was called an ossuary), and then over time store lots and lots of family members' bones in their separate boxes in one tomb. It made a lot more sense to me than burying each body in its own body-sized casket forever.

I'd heard of early Catholic opposition to cremation and cremulation, but also that some cultures did it to mock the belief in resurrection, sort of a, "Let's see anybody resurrect this!" sentiment. I'm not sure about St. Michael, though. He's not traditionally believed to be directly involved in the raising of the dead.