FFXIII - Trophy Question

In FFXIII Chapter 11, does the little green thing hopping around mean anything? What's the

Toppled a green terror and cut an oversized succulent down to size.

mean?

Also, how can you find more Cie'th missions?

Cheers.

http://tinyurl.com/3y76nhd

[spoiler] http://www.youtube.com/watch?v=vYFDmVrvFdA [/spoiler]

Giant Cactaur cie'th stone mission 55, kill it and the achievement is yours.. Cie'th stones are scattered all over gran pulse and by that I mean every area not just the giant green field.