ichnospecies
Explanation
This comic depicts two alien-like creatures (possibly far-future archaeologists) exploring what appears to be an ancient human habitat. One explains the concept of an "ichnospecies" -- a species known only through trace evidence like footprints rather than direct fossils. They discuss how humans created "people-atomizing weapons" and civilization eventually collapsed, leaving no human remains.
The aliens note that the only evidence of humans is crude drawings of "little crab-looking things" (likely stick figures). They observe that human footprints led to a "primitive shelter" containing "drawn pictures of the buildings of local animals, and pens after pens after pens." One alien remarks that "a plastic microbead appears to be unique to this planet" and asks if humans left an imprint on their environment, to which the other replies: "Oh come on, that's a coincidence."
The joke operates on multiple levels. First, it imagines humans becoming an ichnospecies -- known only by traces, not remains -- because they destroyed themselves with weapons of mass destruction. Second, it satirizes how future beings might completely misinterpret human artifacts, seeing office cubicles as "primitive shelters" and stick-figure drawings as accurate depictions of what humans looked like. Third, the punchline about microplastics being dismissed as "a coincidence" satirizes how humans themselves tend to dismiss the massive environmental evidence of their own destructive impact.