astrononion 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. astrononiontemporal range: m eocene - recent scientific classification domain: eukaryota (unranked): sar (unranked): rhizaria superphylum: retaria phylum: foraminifera order: rotaliida family: nonionidae genus: astrononioncushman & 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.