One of the medium's first female practitioners (in 1851 photography was barely ten years old), Anna Atkins learned the skills of photography from William Henry Fox Talbot and Sir John Herschel, two of its inventors and friends of her father, a curator at the newly founded British Museum.
This photograph is a photogram. To make it, Atkins placed a sample of algae on cyanotype paper, a light-sensitive blue paper commonly used for blueprints, and exposed it to sunlight to record an impression of the object. She distributed this work between 1851 and 1854 as part of her British Algae Cyanotype Impressions, the first book illustrated with photographs.