Prismarine Crystal Shards
The best Aquatic Catalyst fuel, and a part in many advanced recipes.
In an 
Aquatic Catalyst a shard gives the most power of any fuel, 20 AP per tick for 75 seconds at purity 1.2. Shards also go into the Prismatic Battery and other advanced recipes.
From a Prismarine Crystal
A 
Prismarine Crystal gives up shards only to an Aquarine Steel Pickaxe that is infused and has its ability on. Punch the crystal with it:
- Each punch puts one or two shards straight into your inventory.
- Each punch also has a 1 in 4 chance to shatter the crystal. If the pickaxe holds at least 100 AP when that happens, it spends 100 AP and the crystal drops three to seven more shards.
A shattered crystal is gone for good. If a crystal is powering a purity build, harvest a different one.
From Budding Prismarine
Budding Prismarine grows clusters that break into shards, so this is the renewable source.
From Prismarine Crystals
Drop 
Кристалл призмарина into a laser beam of purity 2.0 or higher and each one becomes two shards after 8 seconds. A catalyst's own beam tops out at 1.2, so fire it into a Prismarine Crystal and use the beam that comes out, or pass a shard-fuelled catalyst beam through two Focusing Lenses in a row. See Item Transformation.