The Dentate Gyrus
Why this name?
The name comes from the Latin dens, which means tooth, as in dentist. To early anatomists, the dentate gyrus in the human hippocampus looked a little like a row of teeth. All right, so they had colorful imaginations. But this is a pretty big structure and anything which stood out this much was likely to get a name, and a Latin or Greek name at that.
Here's a view of the human hippocampus which shows the "teeth" of the dentate gyrus:
A bit more like the crenulations of a clamshell to my eye, but "Crenulate Gyrus" wouldn't have been a whole lot more helpful, eh?