Brachiopods are one of the most poorly proved phyla, and as such provings of any species would be extremely useful. The 
Cranidae are the highest priority, having no proved members. The Linguidae have only a single trituration, and would also benefit from further provings. The Rhynchonelliformes are the best known Brachiopods, with three remedies, but also could benefit from further provings.
Image Credit: https://commons.wikimedia.org/wiki/File:Usgs_boulder_brachiopods.jpg
