Carterinida
Carterinida is an order of multi-chambered foraminifera within the Globothalamea. Members of this order form hard tests out of thin calcite rods known as spicules, which are held together by a proteinaceous matrix. , the order contains a single family, Carterinidae. The spicules of carterinids have been a source of debate; as they are held together by a protein matrix, it has been suggested that the test is created by agglutinating spicules from the amoebozoan Trichosphaerium. However, life observations of carterinids have failed to find evidence of agglutination, and members of the group have been found to grow on artificial substrates where such spicules were not available from the environment. This suggests the spicules are instead created by the carterinids themselves. The spicules of carterinids are formed of low-magnesium calcite and have "blebs" of organic matter within. Two sizes of spicules are present; smaller spicules are packed tightly between the larger spicules. Spicules appear to have been produced within the cell and moved to their position, as they are rounded and adjacent spicules are not connected. Carterinids were long considered to be represented by a single genus, Carterina. However, the genus Zaninettia was described in 1983 as a second carterinid