This is a paper co-authored by Michael Levin, who is fascinating to begin with. Also this is the first time anyone has mapped electrical patterns across an entire living creature's body. It appears that immortal hydra had more depolarized cells (less negative membrane potential) compared to aging hydra. Given they can induce hydra aging just by changing the temperature, it's an efficient way to study how electrical patterns affect or are affected by (hydra) aging.