[IVY IS PHENOMENOMALLY SURPRISED no not really. She's also holding a petri dish containing a few stripes of a brown, mould-like substance. She holds it out to him.]

Cryptococcus neoformans. It consumes radioactivity for energy in the same way that most plants consume carbon dioxide and water in photosynthesis. This specifically is a mutant strain I've developed for broad-spectrum efficacy and rapidity of growth.