What's up with the Strange Organism in Waking the Ancient?

In the mission Waking the Ancient, around the middle north of the map, there's a neutral critter that burrows as soon as you get anywhere near it. It's definitely selectable; the cursor changed when I moused over it, and I think its name was "Strange Organism" or something like that.

What is it for? Is there a related achievement? Is it maybe part of an Easter egg? Or is it just a red herring?

Please spoiler your answers as appropriate.

Solution 1:

That is

Dehaka

skulking around the edges, checking you out for future activities.

You can also see him on a ledge above your base in the next mission, The Crucible. Notice the missing right arm.