sponges

Microbiologists have long known that the kitchen is an incredibly fertile field for bacterial growth — and a prime source is the kitchen sponge. A recent study of sponges found that even those that are "cleaned" by their users provide a soup of bacteria — some of which are pathogenic.
When it comes to finding new antibiotics, no place is too weird to look. Three separate teams of researchers have identified potentially useful antibiotics from some of the strangest places imaginable: Sponges, sea snails, and marine worms.