Netherstar Shard is a mod that simply makes Netherstars split into x4 pieces for automation purposes.
Wither Skeletons have a 0.05%(1/2000) chance of dropping Netherstar Shards upon player-only kills, which is also affected by looting.
x4 Netherstar Shards in the crafting grid will create a Netherstar, plus you can also de-craft down Netherstars into x4 Netherstar Shards if needed.
It's great for any automation needs, quest rewards or general all round storage, works well with Create for example.