is it normal to see the spine through the shell?

[hippie tortoise owner]

I noticed today that I could see my girls spine through her scutes? I've never seen them before on other tortoises although Im assuming it's because of camera quality I just have no clue

 

[Tom]

That's not the spine. Its just ridges in the keratinous scute material.

 

[Yvonne G]

It's quite obvious on box turtles. The spine is fused to the inside of the carapace.

 

[Pák]

Mine has the same two lines above the last scute.