We report the occurrence of the oldest known multi-chambered trochospiral, planispiral and planispiral/uniserial foraminifera from the Lower to Middle Cambrian deposits in Nova Scotia (Canada). Morphologically, these forms closely resemble modern marsh foraminifera. If these are in fact similar or the same as present marsh foraminifera, their apparent lack of morphological evolution, and the agglutinated and complex multichambered nature of these foraminifera suggest that: 1) these organisms must have some unique characteristics favoring the development of a successful assemblage that appears to have survived to the present, 2) complex chamber arrangements started to develop before 500 Ma, and 3) either these forms are the ancestors to all multi-chambered foraminifera –including the calcareous foraminifera which are the dominant foraminiferal group today – or there was parallel evolution where these went undetected for 200 m.y. when the next occurrence of these chamber arrangements is reported.
Similar foraminifera have been found in Carboniferous and younger deposits where it is clear these were associated with ancient marshes. These fill some of the time gap between the Cambrian forms and modern marsh species.