Echinocyte comes from the Greek word meaning “sea urchin,” which relates to its shell-like appearance. Echinocytes, more commonly referred to as burr cells, are reversible, meaning that this alteration can be the result of the cell’s environment, pH of the medium (including the glass slides on which blood smears are made), the metabolic state of the cell and the use of some chemical substances. Several echinocytes (burr cell) can be seen in this slide; three of them are indicated by the arrows. Notice that the projections are rounded and evenly spaced around the cell. Acanthocytes, by contrast, have irregularly spaced thorn-like projections.