Crenate red blood cell (echinocyte), coloured scanning electron micrograph (SEM). Echinocytes are crenated red blood cells with many blunt spicules or knobs. This condition is caused by hyperosmotic conditions or associated with the pathological condition known as uremia. Echinocytes contain adequate hemoglobin and the spiny knobs are regularly dispersed over the cell surface. Magnification: x2,600 when shortest axis printed at 25 millimetres.