While you see many varieties of the common mold in your house and garden, the scientific word to describe them has a fascinating history. Aspergillus is a genus of 300 or so common molds found in all types of climates around the world. The Aspergillus mold was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. These molds are in the fungus kingdom and while almost all are microscopic, colonies of the mold are easily recognizable and can grow quite large. Viewing the fungi under a microscope, Micheli was reminded of the shape of an aspergillum, which is the Latin word for a holy water sprinkler, itself from Latin spargere meaning to sprinkle, and named the fungus for the shape of the sprinkler.
You can see the similarity above, in the image of a silver aspergillium next to a microscopic view of aspergillus mold next to a colony of aspergillus mold growing on a damp terra cotta pot.
Image of aspergillium courtesy of Andreas Püttmann under a Creative Commons 3.0 license. Image of aspergillus and mold colony courtesy Kathie Hodge and the Cornell University Fungi team.