They have a sand table at his daycare, filled with black iron sand. So they provide magnets for the kids to play with. If they wave the magnet over the sand, the iron filings in the sand all magically jump up onto the magnet. They also have some shells and stones and other similar stuff in the sand.
I'm happily reading away, enjoy the tale of Marcus' enjoyment of the sand and magnet when I get to the following sentence:
Marcus then finds some small pieces of pumas and two shells and begins to pile the black sand on top of them.
Huh? I think. What do big cats have to do with a sand table?
I remained confused for several moments until finally it clicked. Not the plural of puma but pum-as. In other words (or more accurately, the correct spelling) - pumice.
Okay, it makes sense now. But it took a while.
Although I suppose it was a good guess if you didn't know how to spell pumice. It's just that the page is printed out from a computer; where's spellcheck when you need it?