Rugose Corals, often referred to as Horn Coral, are an extinct order of stony corals in the phylum Cnidaria. They lived from the Ordivician period to the end of the Permian period, and can be found worldwide. A new fossil of Siphonophrentis gigantea, a species of Rugosa in the family Streptelasmatidae, has been recovered from the Devonian strata of the Lucas Formation. The fossil gives clues towards the paleobiology of Siphonophrentis, revealing it to have likely anchored itself to the sea bed in the ocean depths. Siphonophrentis gigantea likely had no relationship with Zooxanthellae, a kind of Dinoflagellate that gives modern extant coral their colour and allows them to photosynthesize. These single celled organisms appear to be absent in Siphonophrentis, and it instead received nutrients from a rich amount of biological debris that fell into its habitat. Further comparisons can be made between Siphonophrentis and the extant, cold-water coral Lophelia pertusa.