Anomaly Panoply offers four different 15-ounce mugs featuring eight intricate images of radiolaria from the 1862 monograph on the subject by biologist-artist Ernst Haeckel.
Radiolaria are protozoa that are cool enough to have their own animated documentary (Proteus: A Nineteenth Century Vision), and their own conferences (InterRad XV will be in Japan this year), and that serve as an inspiration for artists from sculptors to landscape architects.
A type of zooplankton, radiolaria are single-celled microscopic animals whose silica shells become skeletal remains that line much of the ocean floor.
Wikipedia explains it better than I could. A fun paragraph to read out loud.
Radiolarians have many needle-like pseudopodia supported by bundles of microtubules, which aid in the radiolarian's buoyancy. The cell nucleus and most other organelles are in the endoplasm, while the ectoplasm is filled with frothy vacuoles and lipid droplets, keeping them buoyant. The radiolarian can often contain symbiotic algae, especially zooxanthellae, which provide most of the cell's energy.
Ernst Haeckel was fairly famous in the 1800s, known as a “biologist, naturalist, philosopher, physician, professor, marine biologist, and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology, including anthropogeny, ecology, phylum, phylogeny, stem cell, and Protista.” (source)
Nowadays Haeckel is known mostly as the source of the quote, “Ontogeny recapitulates phylogeny,” which summarizes his Recapitulation Theory. Basically, he suggests that the stages in the development of an embryo (ontogeny) resemble the stages in the evolution of the animal's ancestors (phylogeny).
For a great article on Haeckel, and to see some more of his gorgeous drawings, check out the Public Domain Review's "Ernst Haeckel and the Unity of Culture" by Dr. Mario A. Di Gregorio.
Here's the entire 1862 monograph, Die Radiolarien (Rhizopoda Radiaria), Eine Monographie von Ernst Haeckel.