It was a delight to profile the wonderful Margaret McFall-Ngai for Nature. She has done some great work on partnerships between a squid and its luminous bacterium, and she’s a powerful force in the world of animal-microbe partnerships. She’s also much-loved in the field; I have never had so many sources practically falling over themselves to sing someone’s praises. McFall-Ngai’s work will feature in my upcoming book, so consider this a little taster.

The aquarium looks empty, but there is something in it. A pair of eyes stick out from the sandy floor, and their owner is easily scooped up into a glass bowl. At first, the creature looks like a hazelnut truffle — small, round and covered in tiny flecks. But with a gentle shake, the flecks of sand fall off to reveal a female Hawaiian bobtail squid (Euprymna scolopes), about the size of a thumb. As she jets furiously around the bowl, discs of pigment bloom and fade over her skin like a living pointillist painting.

There are no other animals in the bowl, but the squid is not alone. Its undersides contain a two-chambered light organ that is full of glowing bacteria called Vibrio fischeri. In the wild, their luminescence is thought to match the moonlight welling down from above and cancel out the squid’s shadow, hiding the animal from predators. From below, the squid is invisible. From above, it is adorable. “They’re just so beautiful,” says Margaret McFall-Ngai, a zoologist at the University of Wisconsin–Madison. “They’re phenomenal lab animals.”