These two images are of the same agglutinated type foraminifer.
The second is a close up illustrating the fact that the test is made up
completely of fine cemented sand grains. This image was scanned and enhanced
from Reiss, Z. and Hottinger, L. The Gulf of
Aqaba: Ecological Micropaleontology. Agglutinating foraminifera
simply incorporate into their organic test any loose, useable material
they can get their pseudopods on from sand to ooids to broken up fossil
material. Spiculosiphon radiata is a carnivorous foraminifera
known to incorporate the tests and shells of its prey as its own agglutinated
test. Agglutinating foraminifera still take on the basic morphologies that
were described earlier, though they may not be so well defined and tend
not to display intricate surface sculpturing due to the granular nature
of the agglutinated particals. There is a grey area between true agglutinated
and secreted tests. Some organic walled foraminifera incorporate small
numbers of agglutinated particles as ornamentations to their tests. The
earliest known foraminifera, identified from the Cambrian, are agglutinators.
It is plausible that the development of secreted tests may have began as
merely the "glue" or cement that originally served to incorporate
the agglutinated particles. Planktonic Foraminifera would have a much greater
chance of survival with a secreted test as they would not have access to
sufficient particles with which to agglutinate a test.