The disembodied head of the sacoglossan sea slug feasts on algae while its old body decomposes, and a new one grows
If you can keep your head when all about you are losing theirs, then it’s unlikely that you are a sacoglossan sea slug (apologies to Rudyard Kipling).
Scientists in Japan have discovered that this species of sea slug can decapitate itself and then regrow an entirely new body, complete with a beating heart and other vital organs.