Actinophrys (ack-tin-off-riss), one of two genera of actinophryid heliozoa. Typically with many stiff radiating arms (not many are visible here) and with large central nucleus. These cells typically eat protozoa, algae and other small swimming microbes. Several cells observed from cooler locations. Differential interference contrast. Material from heated thermal sites of Nymph Creek and Nymph Lake in Yellowstone National Park, photograph by Kathy Sheehan and David Patterson.