Phil Ross has created a a 6×6 mushroom brick arch from Ganoderma lucidum or reishi mushrooms which has been described to be stronger than concrete. Phil Ross has created a a 6×6 mushroom brick arch from Ganoderma lucidum or reishi mushrooms which has been described to be stronger than concrete. However, he doesn’t use the mushroom, or fruiting body of the reishi; he uses mycelium, the fast-growing fibrous roots that make up the vast majority of fungus lifeforms. Mycelium grows fast, and is incredibly durable, waterproof, non-toxic, fire-resistant, and biodegradable. Ross uses it to build bricks by growing mycelium in bags of delicious (to mushrooms) sawdust, before drying them out and cutting them with extremely heavy-duty steel blades. This works because mushrooms digest cellulose in the sawdust, converting it into chitin, the same fiber that insect exoskeletons are made from.