Prismatic Manapearls are the main currency in Nazjatar, and while they have a variety of uses, they can be difficult to farm.
When you finally hit level 120, looking at the long list of all the things you could do next can be kind of overwhelming.
Benthic gear is the catch up mechanism that was introduced in Battle for Azeroth's patch 8.2.
Patch 8.2 brought us a lot of content, and it can be a little overwhelming figuring out what exactly you need to do to be ready for the new raid and what is more optional.
We've seen all sorts of gear catch up mechanics in the past, often tokens that are put in place to help people newly returned to the game be competitive in the latest content, without having to spend weeks grinding out the last raid tier.