Anarcho-communism is a political ideology easy to make fun of and often mocked; notable largely for being probably the single most unlikely system to ever actually occur or work.

Arachno-communism, replacing the prefix for 'anarchy' with the prefix for 'arachnid; or spider' is a semi-commonly invoked mispelling for the purposes of pastiche; implying that instead of communism with no government intervention (somehow) it's communism with spiders (equally somehow.)

SCP-1006 is a long existing SCP that consists of a forest of intelligent, politically minded, collectivist, and fairly pleasant spiders. Being a literal Communist civilisation (Real Communism™ even) but with spiders.

Man with test tube is also a meme featuring somebody looking proud of finding something memey that is considered impressive or new.

So, here, man with test tube has noticed SCP-1006, literal 'Arachno-communism', and is proud because the impossible dream has come to fruition.

This has been an explanation of an image 6 meme layers deep, thank you for reading.

"notable largely for being probably the single most unlikely system to ever actually occur or work."

Idk man, ancom has a lot of rough competition in that department