Sparkleshell Sandcrawler
Drops from Sandclaw Stoneshell. The shells of this particular group of crabs shimmer like gems on the sand. Aquatic type. These pets drop after completing Heroic and above Island Expeditions it seems. Mine was put directly into my inventory with no popup-notification, so check your bags after every completed expedition!
The 
Sparkleshell Sandcrawler is a crab pet obtainable from Island Expeditions on Heroic difficulty or higher.
Guide awaiting review
Complete Heroic Island Expeditions
Run Island Expeditions on Heroic difficulty or above. The Sparkleshell Sandcrawler drops upon completion, but may not trigger a popup notification—check your inventory immediately after each expedition finishes.
Purchase from Auction House
If you prefer not to run expeditions, the Sparkleshell Sandcrawler is cageable and can be purchased from other players on the Auction House.
Alternatively buy from vendor
Visit Sandclaw Stoneshell at 51.8, 51.4 in Nazjatar to purchase the pet directly.
