it be turned on a spit = ?

Context:

Bilbo Baggins: so there I was, at the mercy of three monstrous trolls. And they were all arguing amongst themselves, about how they were going to cook us. Whether it be turned on a spit, or to sit on us one by one, squash us into jelly. They spent so much time arguing the whithertos and the whyfors, that the sun’s first light crept over the top of the trees, and turned them all to stone!

oristarA wrote:

Context:

Bilbo Baggins: so there I was, at the mercy of three monstrous trolls. And they were all arguing amongst themselves, about how they were going to cook us. Whether it be turned on a spit, or to sit on us one by one, squash us into jelly. They spent so much time arguing the whithertos and the whyfors, that the sun’s first light crept over the top of the trees, and turned them all to stone!

That is a metal rod that supports the weight of the meat,
as it is suspended horizontally above a barbeque fire,
turning the meat, rotating it, so that it will slowly cook evenly.

The meat is impaled upon that rod, which then serves as an axis
upon which the meat is rotated for uniform exposure to heat beneath.

Spit roasting

Good picture, to illustrate the point.
I did not know how to do that.