Halloween has gone a bit too far this year. Spiders do not have skeletons.
A rat, yes, but not a spider.
A spider has an exoskeleton. That means chitin (like fingernails or the shell on a shrimp) on the outside, not bones on the inside.
Also, a rat’s ears are made of flesh and skin and cartilage, just like your ears, not bone, and they would rot away with the rest of the rat before you even got to its skeleton. (And there would be nothing left of its tail but a scattering of tiny bones.)
Maybe I am overthinking this.