I think this is a moss, or maybe a liverwort. It's growing low on the trunk of a Coast Live Oak, in a wet portion of trunk. Photo 8 shows the wet spot on the tree.
Host plant: https://www.inaturalist.org/observations/238731859
Photos 1-5 and 7 were edited to have an Auto White Balance in Photoshop (Photoshop's preset).
we spotted a line of Algae formed on the side of the curb by the engineering building. The environment was well watered and close to water pipe.
Photo and Observation via Email by Krisha Amparo De Silva
With Orthotrichum. ID's from @mossgeek.
These mosses were mostly black again on this trip, with just a bit of green still present. Five days ago, they were all green, right after a good rain: