Proceedings of the Zoological Society of London. London, Zoological Society of London., The illustration features a detailed rendering of the marine organism Geodia tumulosa, commonly known as a type of sponge. It presents a complex, textured surface with various irregularities and depressions that reflect the organism's unique structure. The depiction includes small openings and pores characteristic of sponges, suggesting its role in filtering water. Surrounding the main subject are stars and outlined asterisms, perhaps indicating contextual scientific information or illustrating environmental references. The overall composition emphasizes both the intricate details and the biological significance of Geodia tumulosa, as highlighted by the accompanying labels and annotations.