Onyx Egg

Onyx Eggs are quest items that can be turned in to Elder Anli to earn reputation with the Order of the Cloud Serpent. The quest is repeatable. Once you complete the quest It's A..., you will be able to loot the eggs and turn them in. Upon becoming with the Order, you cannot turn them in any more.

These eggs are similar to BC's Netherwing Eggs and WotLK's Everfrost Chips.

Source
This item is looted only on Windward Isle in the Jade Forest in Pandaria.

As a quest objective

 * Onyx To Goodness