The Circle of Life

This mural is a reference to the well known children's' movie The Lion King. In this movie, the monkey Rafiki holds up baby lion Simba in front of the whole kingdom of animals and his parents Mufasa and Sarabi while the song 'The Circle of Life' is played. (This song discusses the food web as a circle of life: a new lion is born, so he must eat prey animals and will eventually have to die and be decomposed, although this part is skimmed over for the kids).

In biology, students learn that carbon is one of the most important elements for life. It is drawn in science classes (shorthand) as a zigzag line, with each vertex representing a carbon atom. Each carbon atom is assumed to have as many hydrogens bonded to it as are necessary to complete its octet (8 electrons or 4 pairs in valence shell). A line next to a main line represents a double bond (atoms share two pairs of electrons) as opposed to a single bond (atoms share one pair of electrons). If other elements are bonded to a carbon chain or ring, their bonds are also shown as lines, but their atomic symbol (representative letter(s), like C for carbon) is written. Therefore, the molecule of benzene depicted (a simple organic molecule) looks like a circle an contains the carbon that is important to life. Additionally, the three double bonds can be written as a circle inside the hexagon of carbon molecules because these carbon molecules have equal electronegativity (pull on electrons), so they share the double bonds equally, so a circle that is equally between all the molecules is a better representation. (This part might only make sense to people who have taken AP Chemistry... The circle is actually formed because the carbon atoms are all sp2 hybridized, leaving one p orbital free. This free p orbital can form a ring shaped pi bond equally between all the carbon molecules; there is actually a circle above and below the main carbon ring because of the two lobes of a p orbital. In benzene, there are three electrons in each ring because there are three pairs of electrons that are shared, so six electrons total, so half of those in each ring is three. See page 440 of the pdf version of the chemistry textbook / page 415 paper version of pdf for a refresher).

More on shorthand carbon molecules: http://dept.harpercollege.edu/chemistry/chm/100/dgodambe/thedisk/chrom/org.htm