"China" wrote in message
...

G'day Nelli,
If it's growing on your roof then it is probably a
'lichen', not a true moss. Lichen is a symbiotic relationship between two
other species. I think its a moss and a bacteria working together, forming
a
colony of very tough plant material that seems to survive most extremes
that
neither species could have survived alone, but I'm not sure which species,

A fungus and a unicellular alga. Sometimes, but rarely, the fungus exists
independently. If it does it looks nothing like the lichen.

R