Sapphire Crab
Drops from Magical Treasure Chest. These crabs build their own shells from small fragments of rocks and gems. Aquatic type. On the you'll probably come across a stranded magic Lionfish which is marked as a treasure.
The 
Sapphire Crab is a battle pet obtained from a Magical Treasure Chest on a small island southwest of Dornogal in the Isle of Dorn, rewarded by helping a stranded fish named Lionel.
Guide awaiting review
Find Lionel the Fish
Head to the small island southwest of Dornogal and find Lionel at 40.62, 59.87 on the north tip of the island, sheltering under a rock pillar.
Push Lionel Into Water
Interact with Lionel to kick him into the water, after which he will ask you for food before he can swim away.
Collect Plump Snapcrabs
Search the shoreline of the same island for 5x 
Plump Snapcrab — they are small and blend in with the sand. Use /tar plump snapcrab to target them more easily.
Feed Lionel and Loot
Return to Lionel at 40.62, 59.87 and feed him the 5 Plump Snapcrabs. He will leave behind a Magical Treasure Chest containing the Sapphire Crab pet.
Tips
This pet is not cageable, so it cannot be obtained on alternate characters via the Auction House.
This treasure is part of the Treasures of the Isle of Dorn meta achievement.
