[3] It is encased in a heavily silicified cell wall, called the frustule, and is identified by its unique theca, raphe and striations, which distinguish it from other diatoms.

[4] They are native to pelagic environments of the Southern Ocean within a temperature range of -1° to 18° C.[5] F. kerguelensis is known to form community chains that consist of 20-100 cells and can be up to 300 μm long.

[6] Fragilariopsis kerguelensis is well preserved in the fossil record and commonly referenced as a paleoceanographic or paleoclimatic proxy.

[5][7] It is an open water species and is found in its highest abundance between the Antarctic Circumpolar Current and the Subtropical Front.

[9][10] Modern assemblages with F. kerguelensis can be used to calculate past sea surface temperature through the use of transfer functions.