The parieto-occipital fissure or sulcus, is an oblique sulcus which demarcates the occipital lobe from the parietal lobe on the medial surface of the cerebral hemisphere 1. The parieto-occipital sulcus joins the calcarine sulcus to form a pattern similar to the letter Y which has been placed sideways

The calcarine fissure is a complete sulcus at the caudal end of the medial surface of the brain. The visual cortex is found here at the back of the brain. The left side receives signals from the right eye and the right side receives signals form the left eye.

Calcarina is a genus of tiny, single-celled marine organisms called foraminifera. They have a calcareous shell and are found in warm, shallow waters. Calcarina foraminifera are important for paleontologists as they are used in environmental and climate research, as well as for reconstructing past marine environments.

If you're referring to the cortex of bone, that would be trabeculae.

The answer is sulcus.