Ektacytometric examination of red blood cells with morphological anomaly is presented. Confocal microscopy of the blood from the patient N. shows the abundance of RBCs in the form of representatives of the Holothuroidea. RBCs from control patients exhibited an elliptical diffraction pattern whereas patient’s N. RBCs generated a diamond shaped diffraction pattern. Erythrocytes of the patient N. have sharply reduced deformability, plasticity and water permeability of membranes. For the first time, we propose to evaluate the plastic properties of the blood cell membrane itself based on the results of the analysis at low shear stress.