The slightly pointy ridge inside the
ear that is tucked just under the frontmost part of the
helix (the ridge the runs from the back of the ear, around the top, and becomes the
daith once it passes under the rook). It can also be seen as the culmination of the edge that demarks the border between the
conch and the
upper conch (the two big flat areas inside the ear).
If a left ear looks something like this, the linked area is the rook:
____
/ _ \
\_ \ |
\ | |
/ _/ |
/
\__/