Cabot ring (A) & Howell-Jolly body (B) found in peripheral blood smear | Jarkeld Medical Centre Alkmaar, hematology department of Laboratory for Clinical Chemistry, Hematology and Immunology. - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=8881942

Cabot ring | J3D3 - CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=60691547

They are believed to be microtubules that are remnants from a mitotic spindle, and their presence indicates an abnormality in the production of red blood cells. Cabot Rings, considerably rare findings, when present are found in the cytoplasm of red blood cells and in most cases, are caused by defects of erythrocytic production and are not commonly found in the blood circulating throughout the body.