How to create vertex at the middle of a group? I am currently working on a model of a cute little microbe with these little green hair things coming out.  Currently, the hair object ends with a ring of vertices, but I want to create a single vertex connected to all of the outside vertices, like how a UV sphere is when it is created.  How do I do that?
The first image is the hair object currently, second is a newly created UV sphere.
With the face selected, press CTRL + F and select Poke Faces

Alternatively, you can inset the face with I and then press M (Merge), and select At Center.

Same result either way: