Information: - A reef is a bar of rock, sand, coral or similar material, lying beneath the surface of water. Reefs may be up to below the surface. - Cambria is a name for Wales, being the Latinised form of the Welsh name for the country, "Cymru". The term was not in use during the Roman period (when Wales had not come into existence as a distinct entity). It emerged later, in the medieval period, after the Anglo-Saxon settlement of much of Britain led to a territorial distinction between the new Anglo-Saxon kingdoms (which would become England) and the remaining Celtic British kingdoms (which would become Wales). Latin being the primary language of scholarship in Western Christendom, writers needed a term to refer to the Celtic British territory and coined Cambria based on the Welsh name for it. - Tommotia is a small shelly fossil from the Early Cambrian Period. Originally, only a cone-shaped shell was recognized, which was originally thought to be an early cephalopod, with either squid-like tentacles or a snail-like foot. More recent investigation has shown that the cone is not the remains of a complete animal, but a sclerite of a larger, soft-bodied animal that would have resembled a chiton or a sea mouse. The fossils called "Camanella" may be another type of sclerite from the same animal. - Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e. a soil containing more than 85% sand-sized particles by mass. - FOSSIL is a standard protocol for allowing serial communication for telecommunications programs under the DOS operating system. FOSSIL is an acronym for "Fido Opus SEAdog Standard Interface Layer". "Fido" refers to FidoBBS, "Opus" refers to Opus-CBCS BBS, and "SEAdog" refers to a Fidonet compatible mailer. The standards document that defines the FOSSIL protocol is maintained by the Fidonet Technical Standards Committee. - The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian periods, respectively. Lapworth, recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods, and placed them in a period of their own. It received international sanction in 1960, when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. - Chitons are marine molluscs of varying size in the class Polyplacophora, formerly known as Amphineura. About 940 extant and 430 fossil species are recognized. - Archaeocyatha or archaeocyathids ( '' ancient cups '' ) / rkiosa / is a taxon of extinct , sessile , reef - building marine organisms of warm tropical and subtropical waters that lived during the early ( lower ) Cambrian period . It is believed that the centre of the Archaeocyatha origin is in East Siberia , where they are first known from the beginning of the Tommotian Age of the Cambrian , 525 million years ago ( mya ) . In other regions of the world , they appeared much later , during the Atdabanian , and quickly diversified into over a hundred families . They became the planet 's very first reef - building animals and are an index fossil for the Lower Cambrian worldwide . - Latin (Latin: ) is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets. - The Cambrian Period (or ) was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established (as Cambrian series) by Adam Sedgwick, who named it after Cambria, the Latinised form of "Cymru", the Welsh name for Wales, where Britain's Cambrian rocks are best exposed. The Cambrian is unique in its unusually high proportion of lagerstatte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods. - Corals are marine invertebrates in the class Anthozoa of phylum Cnidaria. They typically live in compact colonies of many identical individual polyps. The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. - DOS , short for "disk operating system", is an acronym used to describe the family of several very similar command-line computer operating systems for x86-based computers: primarily MS-DOS and PC DOS, but also DR-DOS, FreeDOS, ROM-DOS, and PTS-DOS. None of these systems were officially named "DOS", and indeed "DOS" is a general term for disk operating system. - Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). They work on the premise that, although different sediments may look different depending on the conditions under which they were laid down, they may include the remains of the same species of fossil. If the species concerned were short-lived (in geological terms, lasting a few hundred thousand years), then it is certain that the sediments in question were deposited within that narrow time period. The shorter the lifespan of a species, the more precisely different sediments can be correlated, and so rapidly evolving types of fossils are particularly valuable. The best index fossils are common, easy-to-identify at species level, and have a broad distributionotherwise the likelihood of finding and recognizing one in the two sediments is minor. - In biology, a species (abbreviated sp., with the plural form species abbreviated spp.) is the basic unit of biological classification and a taxonomic rank. A species is often defined as the largest group of organisms in which two individuals can produce fertile offspring, typically by sexual reproduction. While this definition is often adequate, looked at more closely it is often problematic. For example, in a species complex, the boundaries between closely related species become unclear or disappear altogether. Other ways of defining species include similarity of DNA, morphology, or ecological niche. The presence of locally adaptive traits may further subdivide species into infraspecific taxa such as subspecies. - Wales is a country that is part of the United Kingdom and the island of Great Britain. It is bordered by England to the east, the Irish Sea to the north and west, and the Bristol Channel to the south. It had a population in 2011 of 3,063,456 and has a total area of . Wales has over of coastline and is largely mountainous, with its higher peaks in the north and central areas, including Snowdon, its highest summit. The country lies within the north temperate zone and has a changeable, maritime climate. After reading the paragraphs above, we are interested in knowing the entity with which 'archaeocyatha' exhibits the relationship of 'taxon rank'. Find the answer from the choices below. Choices: - branch - class - family - form - kingdom - series - species - tribe
class