Are they difficult to extract? The fish has two right?
If that cup belongs to Don then he's taken a lot of WSB.
Yup, each fish has two. They're not hard to extract if you know what you're doing. If you cleave the heads in half, you can stick your finger in & dig em out. Easiest way to explain is - they're located in that last roundish segment of vertebrate where it connects to the skull. We got some cool looking ones from ARS in the gulf, pargo in Baja, salmon fishing in Monterey, rockfish from Mendocino, of course WSB, etc... Kinda cool since each has it's own shape and size.
Marine biologists use them to study age - they have growth rings like rings in a tree. Generally the older the fish, the bigger the otolith.