The moss and lichen (white/green crust) are safe for your bird to chew and ingest.
We do have a notice on our natural perches about it and a quote and link to an article by our Avian vet, here is the quote and a link to the article.
Some perches may have moss & lichen on them, this is harmless to your bird and as quoted by Peter Wilson (Avian Vet) "They just provide extra nutritional and occupational enrichment." To read the full article on perching
Click Here