Radiolarians. Computer enhanced illustration of radiolarian species. These are one-celled protozoa found in marine plankton. The silicate skeletons seen here are among nature's most beautiful structures. Within each skeleton the radiolarian cell with nucleus is found; protoplasm extends from pores in the skeleton to form long pseudopodia (not seen), and these tiny cells resemble "little suns". As they float, pseudopodia trap food particles and the radiolaria feed. Dead radiolarian skeletons are found in large numbers on the seabed, forming fossil deposits. Illustration taken from Ernst Haeckel's famous treatise: "Art Forms of Nature" (1904).