dents
Your answer is a cross-section. . It is called a cross-section when something has been cut through the middle and you can look inside.
optical discs
There was. They were sold at Winn-Dixie grocery stores - discontinued in the 1990s. It was a oversized round cookie with a rectangular stamp of "DIXIE" in the middle of it, little square indentations covered the rest of the cookie. It tasted like a crisp shortbread with a hint of vanilla.
It is called the MIDDLE, dummy.
The middle of a planet is generally called the 'Core'.
Like a hurricane, the middle of the tornado is called the Eye.
The middle part of an oar is called a LOOM
The middle of a line segment is called a Midpoint.;-)
The middle range of Himalayas is called Himachal range (lesser Himalayas or the Lower Himalayas)
South Africa is not called the middle east.
The Middle East.
The middle layer of the ocean is called the thermocline.