Astrononion

Astrononion is a genus of foraminifera in the family Nonionidae, characterized by an evolute planispiral test with radially stellate structures partly covering the sutures on either side. The test is free, bilaterally symmetrical; periphery broadly rounded; chambers distinct, separated by depressed radial sutures, increasing gradually in size, and usually inflated; aperture a low arched opening at the base of the face of the test. The wall is of finely perforate monolamellar granular calcite.

Astrononion Temporal range: M Eocene - Recent
Scientific classification
Domain:	Eukaryota
(unranked):	SAR
(unranked):	Rhizaria
Superphylum:	Retaria
Phylum:	Foraminifera[1]
Order:	Rotaliida
Family:	Nonionidae
Genus:	Astrononion Cushman & Edwards, 1937

The secondary chamberlets in the original description of Cushman and Edwards 1937 that give the stellate appearance were noted by Loeblich and Tappan as resulting from non-porous flaps that project backwards from each chamber partly covering the preceding suture and umbilical region but leaving a small open cavity beneath, giving the appearance of secondary chamberlets.

Astrononion has a cosmopolitan distribution and is known from the Middle Eocene to the recent. Along with Fujinonion, Laminononion, and Pacinonion, it forms the subfamily Astononioninae.