For 150 years, we have thought lichens were a combination of an alga and a fungus. Now, it has been shown that there are two fungi involved. I learned about it on Facebook, in an article from The Atlantic, published on July 21, 2016, and I needed permission to link it, so I didn't. [That page led to another article on a different topic, the extinction of hundreds of species because of a fungus, in Nautilus, dated December 23, 2016. Go read that one, too.]