Jack set down the torch in the moss, photo-stamped a matsutake with the GPS coordinates, bladed the stem, and capped it in a specimen jar. “And a mushroom’s spores are made from chitin. That’s the hardest naturally made substance on earth. Harder even than steel.”

“Really? But they’re squishy.”

“It depends on the nanostructure and density. It can be harder than steel, I should say.”

“Okay.”

“And a lot of scientists believe fungi originally came from space.”

Mia pretended her flashlight into a lightsaber and swung it around. “Do you believe that?”

“Maybe. Oh, and get this. A certain kind of mushroom contains a compound that can give you crazy dreams—and you don’t even need to go to sleep to experience them.”

“You dream with your eyes open? Can I do that?”

“Well . . . no. It can be dangerous. And illegal.” Jack hurried his words. “But! That same compound—psilocybin—might be a great way to fight depression. There are some clinical trials happening right now.”

“You mean like what Mom gets? The blues?”

“Yeah.”

“Mushrooms can make her better? Can I pick some for her, then? Like a bouquet?”

“It doesn’t work like that, I’m afraid,” Jack said, the energy falling out of his voice. “But that’s a nice thought, sweetie.”

They tromped in silence for a few minutes, then Mia said, “I found something! I’ve got one!”

Not one, but many. Dozens and dozens that made up a circle of mushrooms, twenty meters in circumference. They pushed aside ferns and peeked behind logs to find them all and trace the perimeter. It was a fairy ring, Jack explained. “Some people think it means good luck and some people think it means bad luck.”

“What do you think?”

“Good luck. Definitely.”

He explained how you could see the sporocarps above, but there was mycelium below that bound them all. “In other words, all of these mushrooms are separate but together. They’re the same fungus.”

“Separate but together,” she said. “Like you, me, and Mom.”

“Yeah. Sure. A family.”

Jack got down on his knees, muddying his jeans, and crept along, lifting branches, brushing aside fir needles, peering under logs and into stump cavities, straining his eyes to take in every inch of the forest floor. Maybe fifteen minutes passed without him really registering anything other than the next fungus sample.

Then he noticed a voice calling to him with impatience. “Daddy? I said, Daddy!”

“Yeah?” He sat up and rubbed the bridge of his nose.

“I’ve called for you like a hundred times.”

“Sorry.” He swung his flashlight toward the sound of her voice. She stood twenty yards away, her back to him. “I’m just concentrating.”

“I think I found something.”

“A mushroom?”

“No. A hole.”

“I don’t have time for holes right now—okay, sweetie? The sooner I get this survey done, the sooner we can get back home.”