The protective covering of the brain
that provides passageways for cerebrospinal fluid (CSF) to drain into the
superior sagittal sinus is called the arachnoid mater.
To add, the arachnoid mater is the middle
of three layers that make up the meninges, or membranes, that surround the spinal
cord and brain.
I am guessing an Ecological Relationship as it is dependent on it's environment