Wikipedia
Fissurina is a genus of lichenized fungi in the family Graphidaceae. The genus was first described by the French botanist Antoine Laurent Apollinaire Fée in an 1825 publication.
Fissurina is a unilocular (single chambered) calcareous foram genus, similar in general form to Lagena, but included in the nodosariacean family Ellipsolagenidae, Lagenida.
The test is rounded to ovate in outline, oval to lenticular in section, and may have one or more peripheral keels. Wall calcareous, hyaline, finely perforate, surface smooth, with random or regularly aligned punctae. Aerture terminal, ovate to slitlike, within a slightly depressed fissure at the test apex, provided internally with an entosolenian tube that may be central or may curve toward one side of the test and may be attached to the inner wall. Stratigraphic range: Cretaceous to Holocene.