The fog came up the cliff a little after six, the way it did most evenings in October, and the house woke all at once, thirsty.
Fungus was up first. She always was. Water ran into the loose weave of the medulla and every one of her threads swelled together, so the whole house seemed to take a breath, and by the time the top of the fog had reached the walking path she had the table set and a dish of last week’s mannitol warming. Under the table, the tip of her that worked through every wet minute crept on toward the seaward edge of the rock.
Algae came in green and already talking. He set a dish of ribitol between them, made that morning, and slid it to her side before he sat down.
“You should have seen it, love. The fog burned off by nine, and the whole headland went gold, and the light came down through the roof all orange, like living inside a persimmon.”
“I put a second coat on Tuesday,” Fungus said.
“I could tell. I didn’t get stung once.”
She made the orange herself, a pigment called parietin that she laid into the upper cortex to blunt the coastal sun. Too thin and the light bleached him; too thick and he went pale and sulky by noon. She had been adjusting it for three hundred years and still got it wrong after a rainy spell.
“Around eleven a gull stood on the roof,” Algae said, reaching for his water. “Big one. Its shadow went over me like weather, and I sat there in the dark wondering if that was it for the day, and then it lifted off and the sun hit me so hard I fixed carbon until my pyrenoid ached. You’d have thought I was a meadow.”
“How long did you get?”
“Three hours, nearly.” He looked proud of it. After that the wind had come off the water and dried the house to a crisp, and they had both stopped mid-thought, as they did most afternoons, and stayed stopped until the fog returned. Neither of them minded. Fungus liked to say that anyone who couldn’t stop had no business living on a rock.
“And you?”
“Seaward side.” She took a scoop of his ribitol and turned it into mannitol on the way to her plate, which she did with every bite, so that it went into the pantry in a form he couldn’t take back out. He had never once mentioned it. “There’s a seam of feldspar past the old crack. Soft stuff. I put acid on it this morning and it gave by lunch.”
“Oxalic?”
“What else?” She sounded pleased with herself. “Got a thread into the grain and pried. Three microns, maybe four.”
“Four microns,” Algae said. “That’s a lot of house.”
“It’s prothallus. Nobody lives there yet.” The edge of her territory was always her alone, dark threads out ahead with no green in them, holding ground for later. “When it firms up, you can send a few of the children out.”
“They’re dividing like mad. The little ones by the north wall have no manners at all.” He ate for a while, and then he laughed into his ribitol. “I forgot. We had visitors.”
“The walking trail?”
“Four of them, teenagers, around ten. Loud. One of them sat right down on the rock, a girl, and put her hand flat on the roof.” He spread his own across the table to show her. “The light went out. Like the gull, but warmer. And she said to the others, look at this plant, it’s like somebody painted it on.”
Under the table, the tip of her stopped.
“A plant.”
“A plant.”
“I’m closer to her than I am to any plant,” Fungus said. “Her lot and mine share a branch. Fungi and animals came off the same line, long after the plants went their own way. She sat on her own cousin and called her a plant.” She set her fork down. “And this house carries my name. Every lichen on this coast is named for its fungus. Every one.”
Algae was laughing too hard to answer. He pushed the dish of ribitol back across to her side, though she had plenty, and wiped his eyes.
“I’ll take it,” he said. “I’m the nearest thing to a plant at this table. Same green family, if you go back far enough. That’s practically a compliment for me.”
“You would think so.”
“She meant it nicely. She had a hand the size of a whole colony and she couldn’t make one sugar with it. Had to eat something that could.”
Fungus considered this. “They can’t dry out, either.”
“Not once. They’d die.”
“Can’t eat rock.”
“Can’t stay put. They have to keep walking off to find more.” He shook his head. “All that size, and they spend it on walking.”
“Not a well-evolved lifeform,” Fungus said primly.
“Young, though.”
She pulled the dish toward her. “Give them four hundred million years.”