Trilobite and brachiopod fossils have been found in Gregory's Cave. Among them are trilobites such as "Leonaspis", "Raphiophorus" and a fragmentary harpetid trilobite. Trilobite fossils have been found on Langlade. Most of the Cambrian stratigraphy is based on the use of trilobite marker fossils. Trilobite fossils are found worldwide, with many thousands of known species. Less ambiguous references to trilobite fossils can be found in Chinese sources. Huge radioactive footprints and a prehistoric trilobite are discovered. Trilobite zones allow biostratigraphic correlation in the Cambrian. The egg is about across, and hatches into a larva that superficially resembles a trilobite. Most known families of coral and trilobite became extinct. Late Ordovician survivors account for all post-Ordovician trilobite groups except the Harpetida. The Phacopina comprise a suborder of the trilobite order Phacopida. The heat of the Cambrian sea may have contributed to trilobite emergence. In September 2016, Electrolux introduced the successor to the Trilobite, the MotionSense. It correlates well with the occurrence of widespread graptolite, conodont, and trilobite species.