Even if placozoans are not the oldest animals, they’re still some of the weirdest. Trichoplax’s genome, published in 2008, contained a surprising twist, Athula Wikramayake, a developmental biologist at the University of Miami, says. Despite having the simplest bodies of all animals, placozoans carry many of the same genes as humans do, including numerous genes involved in building brains and other complex organs, like those in the digestive system. Placozoans contain far more genetic complexity than scientists ever guessed, Wikramayake says. “The question is, what are they doing with it?” Pixies have a whopping 1 hit point. But their innate ability to turn invisible, 15 AC, andselection of spells make them difficult to catch. Of course, pixies are social creatures who live together in groups, so turning a dagger to one pixie could mean being swarmed by a dozen others. Using pixies in your game When the team leaves for the lab, I retreat to my dorm room at the Monterey hostel, defeated. I am not hardcore enough to hunt wild Trichoplax, I think. I take a nap. At 11:32 p.m., my phone lights up. It’s a video text showing Zhong and Soto Montoya huddled around the microscope, looking buoyant. Zhong has found a Trichoplax. “That’s it, 110 percent,” Prakash says. “It’s beautiful, beautiful!” On a computer screen that shows the display from the microscope, Trichoplax looks like a glowing, pulsing orb surrounded by cosmic protoplasm. Soto Montoya finds a second, bigger animal. They sign off and keep scanning each slide, one by one, until 4 a.m.

While the current selection of hags top out at a challenge rating of 7, a coven of three hags vastly increases the difficult of an encounter (see "Hag Covens" below). Hag CovensWhen hags must work together, they form covens, in spite of their selfish natures. A coven is made up of hags of any type, all of whom are equals within the group. However, each of the hags continues to desire more personal power. Smith and her colleagues have found a series of evenly spaced cells along Trichoplax’s periphery that she thinks may help herd the cilia by secreting a chemical signal that makes them pause. The chemicals are similar to the neurotransmitters that regulate appetite and contractions of the digestive tract in humans, according to the neurobiologist Diego Bohórquez, of Duke University. When many animals are grouped together, a single Trichoplax releasing the chemical can trigger its neighbors to secrete as well, causing the whole group to slow down and graze on algae “much like bison on a grassy plain in Yellowstone,” Borhórquez wrote in a 2018 article in the scientific journal Brain Research. Shifting through the party's camp as fast as the wind, they tied the shoe strings of the heaviest character together. Then one of the feys took a dagger from the camp to distract the guard, so the other quiskling can move all important adventuring gear in the guard's bag. For elegant finish they took a beautiful ring from one of the sorcerers (the party's ring of jumping, gifted to them by two rogue kids) and braided the hair of two characters. Use joints, bones and muscles to build creatures that are only limited by your imagination. Watch how the combination of a neural network and a genetic algorithm can enable your creatures to "learn" and improve at their given tasks all on their own.

Night hags, however, are strongest when they're aware of their enemies. They can enter the Ethereal Planeto inflict nightmares on a creature, lowering their hit point maximum and depriving them of the benefits of a long rest. Using hags in your game The tasks include running, jumping, climbing and flying. Can you build the ultimate creature that is good at all of the tasks? The test took place in one of Prakash’s recent inventions, a Ferris wheel–inspired contraption he calls the Gravity Machine. Composed of a thin plastic wheel full of water, the Gravity Machine rotates vertically in front of a powerful microscope, acting as an aquatic treadmill for microorganisms. Even in the narrow disk, which is less than half an inch wide, Trichoplax is so small that finding it with the naked eye is like searching for a dust mote in a gymnasium.

Night hag: Once creatures of the Feywild, night hags were exiled to Hades. These creatures befoul all good things, turning love into obsession and generosity to selfishness.

Like Trichoplax, Prakash and his 15 to 20 graduate students, postdocs, and lab technicians seem to move in a thousand directions at once. One day I watched as Prakash taught a new doctoral student, Hannah Rosen, how to suction Trichoplax out of a petri dish full of seawater and settle them on a slide. Move too slowly, and the animal will attach itself stubbornly to the syringe, Prakash explained, his hand darting toward the slide with the speed and precision of a heron’s beak. To prevent Trichoplax from creeping off the slides, Prakash has built a small well out of double-sided tape, which he calls a jail. “For the first 30 designs we made, it figured out how to break out of the jail,” he said, with obvious fondness. “It can slip under even the tiniest of gaps. It’s quite remarkable.”While Prakash agrees that the animal holds great promise for biomedical research, his pursuit of Trichoplax is about more than its practical applications. “I also study it for its beauty and elegance,” he says.