Lichen

Thanks Alex. I just joined.

Thanks. I'll let you know what I find in my book.

Good question, AlexKonig. I have never thought of that, but my assumption would be they are two different lichens just co-existing on the same surface. I am not good at lichens too, but I think if they die, they would just start to dry out and wear off in the middle of the “colony”. As we can see one of the orange lichens has a hole in the middle, while the grey ones seem quite healthy. I’ll try to check this in my botany book. I have read that lichens are composed of a fungus or mold and an alga, which have symbiotic relationships. The fungus provides nutrients and minerals, since it has hyphal structure, which gives it the ability to penetrate through walls or stones or tree trunks; and the alga produces organic carbon sugars through photosynthesis, since it has chlorophyll.