Lichen on the roof

At the hardware store...

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Customer: Need some spray to get rid of lichen.

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Assistant: Where is it?

Foliose lichen

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Customer: On the roof.

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Assistant: And what’s the roof made of?

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Customer: Colorsteel.

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Assistant: Sodium hypochlorite. Dilute it to 2%.

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Customer: Any kind of lichen?

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Voice-over

Cross-section:
fungus and algae

There are between 13,000 and 17,000 species of lichens. Classification is difficult because lichens are a combination of fungus and algae. Sometimes a cyanobacterium is in the mix. It's a symbiotic relationship with the fungus providing the base and moisture, the algae providing the mineral nutrients. Lichens date back to 400 or maybe even 600 million years.

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