Science Art: Fig. 10 (Theil eines Stockes von Carchesium polypinum mit zwei Individuen), by Carl Gegenbaur,1870

This is a little critter known as Carchesium polypinum, less formally a “stalked ciliate,” an organism that forms colonies that look like teensy tinesy trees, or maybe ferns, but found in little drops of water. This particular one was found in Grundzüge der vergleichenden Anatomie, published in Leipzig and preserved in the Heidelberg University Library.