A drawing made with red and black felt-tip pens on a classroom or conference paper drawing board. The drawing shows a spherical cow on skis, with a caption: "Approksimoidaan pyöreä lehmä" (Finnish for: "We approximate a spherical cow"). Found at the conference and sauna premises at the top floor of Domus Academica, Etu-Töölö, Helsinki, Finland. The drawing itself was not drawn by me and I don't know who drew it, but I feel it is simple enough to be considered public, and I don't think whoever drew it intended to gain any benefit from exclusive ownership of copyright.