I should probably ask a pro about this.

Yeast in the fridge might have come with me from the old house.

It still produces a nice bubbly mass when mixed warm, sugary liquid. That means it's still living and functional yeast, right? Not that it's, say, zombie yeast, or powdered evil, or sea monkeys, right?

And if it's not, then is there any health risk inherent in sea monkey bread?