=====Calcar avis=====
{{ http://upload.wikimedia.org/wikipedia/commons/4/49/Gray739-emphasizing-calcar-avis.png?400}}The calcar avis, previously known as the hippocampus minor, is an involution of the wall of the [[lateral ventricle]]'s posterior cornu produced by the [[calcarine fissure]].

It is sometimes visible on ultra sonogram and can resemble a clot.