Radiolarians are single-celled marine organisms known for their intricate silica skeletons. They belong to the group of protists and are primarily found in oceanic waters. These microscopic creatures play a crucial role in the marine ecosystem, contributing to the ocean's food web and carbon cycling. Radiolarians have a unique structure, often featuring spiny or ornate shapes that can be observed under a microscope. They capture food through a process called phagocytosis, where they engulf smaller organisms. Their remains contribute to the formation of sedimentary rocks, making them important for geological studies.