Abnormal test development in foraminifers is observed and environmental factors are suggested to be the main cause. Most of the abnormalities are aberrant test morphologies. In some cases twin, triplet and quadruplet formations are observed. The twins may sometimes be formed by two different species. In the framework of this study, foraminifer fauna of a submarine spring (Pamucak Cove, north-western Kuşadası, Aydın) was determined. A rich population of Amphistegina lobifera Larsen was found. Individuals with abnormal morphologies were also observed, but the most striking abnormality was the togetherness observed between two different families, Vertebralina striata d'Orbigny (Ficherinidae: Nodobacularinellinae) and Coscinospira hemprichii Ehrenberg (Peneroplidae).
