''Miliamellus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

benthic foraminifera with tests made of imperforate

opal Opal is a hydrated amorphous form of silicon dioxide, silica (SiO2·''n''H2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a ...

ine silica. It is the only genus in the order Silicoloculinida and the family Silicoloculinidae. It is sometimes referred to by the junior synonym ''Silicoloculina''. The family Silicoloculinidae, named by Resig, ''et al.'', 1980, is characterized by tests that resemble those of the imperforate calcareous Miliolidae, or the finely agglutinated Rzehakinidae in which chambers are about half a coil in length and arranged in various planes. Resig et al. named the genus ''Silicoloculina'' for specimens recovered from below the

carbonate compensation depth The carbonate compensation depth (CCD) is the depth, in the oceans, at which the rate of supply of calcium carbonates matches the rate of solvation. That is, solvation 'compensates' supply. Below the CCD solvation is faster, so that carbonate pa ...

in the

Scotia Sea The Scotia Sea is a sea located at the northern edge of the Southern Ocean at its boundary with the South Atlantic Ocean. It is bounded on the west by the Drake Passage and on the north, east, and south by the Scotia Arc, an undersea ridge and is ...

and the Peru-Chile Trench. Loeblich and Tappan synonymised this genus with ''Miliamellus'' in 1987. ''Miliammellus'', named by Saidova and Burmistrova, 1978, has a small ovoid test, up to 0.5 mm long with chambers arranged as in the miliolid '' Quinqueloculina''. Chambers are slightly more than half a coil in length, resulting in successive whorls being offset, and are widest at their base, narrowing toward the aperture, a low arch at the end of the final chamber. ''Miliammellus'' has a range from the Upper Miocene to recent and has been found in the Bering Sea, Antarctic, north and central Pacific, and Indian Oceans at abyssal depths below 4,000 m. The type species is ''Miliammellus legis'' Saidova and Burmistrova, 1978. Its test ultrastructure consists of small (5μm by 0.3μm), hollow rods of silica arranged in subparallel sheets, with an outer and inner organic membrane. The outer and inner organic layers are each approximately 0.1μm in thickness. The middle silica layer is about 19μm thick in total; it is further broken down into an outer, inner, and middle silica subunit. The outer and inner silica subunits are each approximately 0.2μm thick and consist of hollow silica rods arranged in subparallel sheets, with the elongation parallel to the surface. The middle silica subunit is approximately 18μm thick and consists of a randomly oriented lattice of hollow silica rods. No organic material is found within the open spaces between rods. In overall shape as well as in ultrastructure, ''Miliamellus'' resembles miliolilid foraminifera. However, the ultrastructure differs in that the rods of miliolid test walls are solid rather than hollow, smaller, and of course are made of

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

References

* Systematics of modern foraminifera, from Loeblich and Tappan (1992), in Barun K. Sen Gupta 200
Modern Foraminifera
* Forminiferal Genera and their Classification by Alfred R. Loeblich Jr and Helen Tappan, 1988

Miocene life Silicoloculinida Foraminifera genera Silicoloculinidae Radiolarian genera {{foram-stub