Went out on the trail and happened across two fallen log pieces, both have a great natural look and both have lichen/mossy stuff on them. I have seen that people pick them up and cook them for some time to sanitize for their enclosures- but what is the tried and true process for it?

is there a way I can do it while keeping the bark/lichen look?

Both piwces are a littlw damp, and both smaller than a foot in length.