Star Shards are the premium currency in Abyss, used primarily to reroll your character's race and unlock additional race slots. Acquiring enough Star Shards requires a mix of consistent activities and one-time rewards scattered across the game world.
Quick answer: Complete quests from NPCs like the Kraken, Mr. Black, and Virelia; unlock achievements by opening the ribbon icon on the left side of your screen; open treasure chests found throughout the map; fill out the Bestiary by catching new fish and claiming rewards from Richard in the Forgotten Dome; and level up to receive small Star Shard rewards automatically.

Complete Quests from NPCs
Quests are the most reliable way to earn Star Shards regularly. The Kraken in the Forgotten Dome offers a series of main quests that reward you with varying amounts of Star Shards. Other NPCs, such as Mr. Black, Virelia, and Marcus, also provide quest chains that grant Star Shards upon completion.
Most quests ask you to reach a certain level, catch specific fish, or explore new areas. The rewards scale with quest difficulty, so prioritize completing as many quests as possible to build up your Star Shard balance. Quests also encourage you to catch fish, which contributes to leveling up and earning additional Star Shards through that system.

Unlock Achievements
Achievements provide another consistent source of Star Shards. Open the achievements tab by clicking the ribbon icon on the top left side of your screen. Each achievement has multiple levels, allowing you to complete them more than once and earn more Star Shards as you progress.
Achievements cover a wide range of activities, from catching certain fish to exploring specific areas. Check back regularly to claim rewards as you unlock new achievement tiers.

Open Treasure Chests
Treasure chests are scattered throughout the Abyss map, and opening them yields Star Shards along with experience points. Each chest can grant anywhere from 5 to 15 Star Shards. Chests appear in the spawn area and around the map, including inside the safe domes.
Chests respawn after some time, making them a reliable way to farm Star Shards regularly. When swimming in the ocean to locate chests, watch out for puffer fish, which can kill you if you are not careful.

Fill Out the Bestiary
The Bestiary tracks all the fish you have caught in Abyss. Every time you catch a new type of fish, it gets added to your Bestiary. Filling out entries rewards you with Star Shards.
Check your Bestiary progress by talking to Richard in the Forgotten Dome. He shows you which fish you have caught and which ones you still need to find. The more fish you catch, the more Star Shards you earn from Bestiary rewards.

Level Up Your Character
Every time you level up, you receive a small amount of Star Shards as a reward. Leveling up happens naturally as you catch fish and complete quests, so this method runs in the background while you pursue other activities.
Random Chests While Fishing
When you are fishing, there is a small chance that a chest icon will appear on your fishing bar. If you manage to catch both the fish and grab the chest icon at the same time, you receive bonus rewards that can include Star Shards.
Redeem Active Codes
Codes provide an easy way to get your first batch of Star Shards. The code RELEASE gives you 100 Star Shards, 5 Small Oxygen Pods, and 1 Speed Potion. To redeem it, click the settings icon in the game menu, scroll down to the code redemption box, enter the code exactly as shown, and click redeem.
Codes are case-sensitive, so enter them exactly as listed. The RELEASE code gives you enough Star Shards for one free race reroll, which is useful if you are not happy with your starting race.

Buy Star Shards with Robux
If you have Robux to spare, you can purchase Star Shard packages in the Exclusive Shop. Open the shop by clicking the shopping trolley icon on the top left side of your screen. Several packages are available, ranging from 100 Star Shards for 49 Robux to 4,000 Star Shards for 1,199 Robux.
The Starter Pack (79 Robux) includes 1,000 Coins, 500 Star Shards, 2 Oxygen Shards, and 2 Speed Potions. The Diver's Pack (349 Robux) includes 1,000 Star Shards, 5 Void Shards, 5 Oxygen Shards, and 10 Speed Potions.

How to Use Star Shards
The main use for Star Shards is to reroll your race. Races are divided into different rarity levels and grant special abilities and bonuses. Each race reroll costs 100 Star Shards. Common races include Poop, Coral, and Elf. Uncommon races include Monkey, Cyclops, and Fish. Rare races include Puffer, Spirit, and Narwhal. Epic races include Crab and Anglerfish, with a guaranteed drop after 18 rerolls. Legendary races include Vampire Squid and Shark, with a guaranteed drop after 48 rerolls. Mythical races include Kraken and Sea Angel.
You can also use Star Shards to unlock additional race slots. By default, you have one race slot. Unlocking the second slot costs 1,000 Star Shards, and unlocking the third slot costs 5,000 Star Shards.
Another use for Star Shards is to speed up geode cracking. When you collect geodes, you need to take them to Virelia to crack them open. Geodes take time to open, but you can spend Star Shards to speed up the process instantly. Longer times require more Star Shards. However, saving your Star Shards for race rerolls is generally more beneficial, as races make a bigger difference in your gameplay.
Focus on completing quests, unlocking achievements, and opening treasure chests to build up your Star Shard balance. Use your Star Shards primarily for race rerolls to improve your character's abilities and bonuses.