An Anomalocaris explores a Middle Cambrian ocean floor about 500 million years ago. Growing to over three feet long, Anomalocaris is believed to have been a predator whose diet included trilobites. Anomalocaris may have also been one of the earliest arthropods. . . This image includes an Olenoides serratus trilobite and sponges genus Vauxia and Wapkia. The small, flower-like animals (yes, like the sponges they are rooted animals) are from the genus Dinomischus. Above and behind the Anomalocaris is an ancient jellyfish.