Robin,

They sound very much like my memory of dimpled nipples.  I thought
dimpled nipples need not be flat, they simply have a portion that flips
in and out, leaving a moist, macerated site with lactation.

The Lactation Institute sells a product called a Dimple Ring that holds
the "shy" part of the nipple out by compressing around the
nipple base / areola to allow time to air dry before it "hides" again.

Makes me think of that cute comic "inverted nipples? no just shy" or
something like that.

Carla