These small urchins are all considered to be Paraselenia poehlii. They come in red and brown forms that tend to be found in different areas. The red ones are usually found under rocks and dead coral, most often on seaward reefs, while the brown ones tend to favor lagoon and pinnacle reefs. The species might be worth another look.
Underside.
The brown form.
Created 16 June 2018
Updated 15 January 2023