Shadow Biosphere
The typical Shadow Biology Department is housed in a building coated in a thin layer of desert varnish which renders it invisible to normal-world university staff.
The typical Shadow Biology Department is housed in a building coated in a thin layer of desert varnish which renders it invisible to normal-world university staff.
A shadow biosphere is "a hypothetical microbial biosphere of Earth that uses radically different biochemical and molecular processes than currently known life. Although life on Earth is relatively well-studied, the shadow biosphere may still remain unnoticed because the exploration of the microbial world targets primarily the biochemistry of the macro-organisms." Because organisms based on RNA would not have ribosomes, which are usually used to detect living microorganisms, they would be difficult to find in normal circumstances.
The comic suggests that this hypothetical biosphere exists, and its study is funded by "shadow biotech" corporations. The field would be called "shadow biology", so people that study it would be "shadow biologists". However, this is reinterpreted to mean "shadow" biologist, meaning that anyone that studies it becomes undetectable. A "shadowy" figure, presumably a shadow biologist, is telling this to Megan and Cueball, but they are not shadow biologists and can't hear him.
If people who study the shadow biosphere become part of it, then it will be very hard to get a lot of evidence without becoming it.
The title text references desert varnish, an orange-yellow to black coating found on exposed rock surfaces in arid environments, which has been suggested as a potential candidate for a shadow biosphere. Unless a building was made with already-varnished rocks, it would be impractical to cover a building in desert varnish (it forms naturally on rocks over thousands of years). Ignoring its impracticality, the joke is that if a building were covered in desert varnish, it would supposedly be invisible to biologists who don't study the shadow biosphere.