I found mine in the bone fields also. Plus I found one up on a ledge near the DRF. (screenshot removed as it was the wrong one.)
That is not a Mesmer egg.
That is Coral.
You are correct BippityBop. I put in the wrong screenshot. Anyway, I did find three of them in the Lost River, and hatched them in an Alien Containment vessel (with some Hoopfish).
Mesmers and Hoopfish
What do you think?