- Cell has a deep transverse furrow (cingulum). It makes a descending left spiral of 1.8-1.9 turns.
- Solitary cell is ellipsoidal, slightly flattened dorso-ventrally.
- Nucleus is located anteriorly.
- Cells form chain under optimum growth condition. Chain is short, consisting of less than 8 cells (rarely of 16 cells). Cells in a chain are compressed anterio-posteriorly.
- Chloroplast are numerous, yellow-brown and rod-shaped or ellipsoidal.
Solitary cell
Chain forming cell
（in 4 cells）
“Cochlo” photomicrographs with various optical sections（upper： solitary cell，lower： 2 cells chain）
