The comparison of the choroid plexus to a worm is very common.
The whole structure is known as the tela vasculosa, or choroid plexus of the fourth ventricle (fig. 250, chd 4).
They are found in one or both of the lateral ventricles, enveloped in the folds of the choroid plexus.
choroid plexus n.
A vascular proliferation of the cerebral ventricles that serves to regulate intraventricular pressure by secretion or absorption of cerebrospinal fluid.