im thinking a primitive villiage/warcamp for an orc tribe or barbaric humans or whatever.
a few goodies would be a wooden wall with wooden spikes pointing out, a squat wooden tower, huts, a huuge fire, religous alters or something maybe, just the whole barbarian getup

maybe some pieces from various primitive cultures, various dwellings (mud/grass huts, tents, longhouses)

Lessee...

SeaWorks: Skull Cove has:

Small stone altar
Stone henge
Big hut
Smaller huts
Savage-looking idol
Obelisks (whole and broken)
Raft
Outrigger Canoe
Foliage (trees, grass)

There's also a wooden fort in there, but it might look a bit too "civilized" for your tastes.

Still...I can't help but think that a lot of what you're asking is in the Cove.