as explained above it's from the Thing. I'm each dish is each person's blood, because all the cells of the Thing will react to stimuli even if it's not actually part of the being. Jon's gonna poke them with a hot rod because even the blood of the Thing will cause the entity to react.

sorry I don't think that was the best explanation but I hope it makes sense ;=;

The Thing 1982: https://www.imdb.com/title/tt0084787

If you didn't watch it before (and like cosmic/body horror), this is as good as a movie can possibly get.

Honestly the scene is worth watching. Sexy dude with the beard explains it all in the first minute. If you're squeamish about blood, you can quit watching as soon as he's done explaining. Nothing scary happens until 3:50