Crenate red blood cells (echinocytes), coloured scanning electron micrograph (SEM). A few normal red blood cells are also seen. 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: x600 when shortest axis printed at 25 millimetres.