The Prismarine Upgrade

There are currently many items that look great and are unique but serve almost no purpose in Minecraft.
Take Prismarine, for instance, which is used for only a few blocks. 
My idea is to introduce an upgrade similar to the Diamond to Netherite progression, that turns the Turtle Shell into a Prismarine version. This would require a smithing template featuring a nautilus shell texture, perhaps found via archaeology in underwater caves, to reinforce the theme of extended underwater breathing.
The helmet could provide effects similar to a Conduit (though less powerful) or even allow the player to swim faster.