Members of this order secrete tiny chambered shells which are very
useful microfossils. The forams are predominantly marine organisms and
have shells composed of chitin, silica, or calcium carbonate. In
addition, some forms construct a shell of sand grains or some other
material which is cemented together by a sticky substance that is
secreted by the animal.
Forams are very abundant in the rocks of Texas and particularly so in
rocks of Mesozoic and Cenozoic age. The most numerous and easily
observed Paleozoic foraminiferans are the fusulinids (fig. 9a), and
their small spindle-shaped remains are very abundant in many of the
Pennsylvanian limestones of north-central and Trans-Pecos Texas. Some
typical Texas forams are illustrated in figure 9.