You can find the egg which give you Terky in the borean Tundra, in a marine cave at the Riplash Ruins. Coord of the Cave are 56 - 88.
The entrance is really tricky to find.
When you are at the coord, you can see in front of the entrance
- A colone
- 2 red Seaweed
- severals green Seaweed
- 2 purple Seaweed when you go further.
- you have to go further and up to get in the cave.
The egg in on the ground, behind the altar.
(big thanks to Maijill-kirin tor / Eiji-Chants éternels / and Reddit-hyjal who find it first)http://imgur.com/a/GJYoD