Marbles. Yes. Wow. Gosh.
I know Marbles has his fans. He's one of the Rock Lords that people seem to remember, perhaps due to how striking he looks. Striking in that he's got a head that looks incredibly rude.
The head's probably the best place to start. It looks really out of place amongst the other Rock Lords - the facial features are much larger, with bulging eyes, big eyebrows and uh... the top of his head. Whatever's going on there. But we know for a fact that this wasn't the plan.
(L to R - Cartoon head, Prototype 1, Prototype 2, This Island Earth alien)
Originally, Marbles was going to have a head that matched his cartoon appearance the prototype that appears in various catalogues confirms this. Clearly at some point late in the planning stage someone said "No, here's a better design" and slapped their love spuds onto the table. This was an actual choice made by actual human beings who weren't (we assume) forced to do this at gunpoint. It has been said that he looks like the aliens from 'This Island Earth', but I don't quite see it myself.
Anyone who bought a Marbles due to his portrayal as the young, handsome lead in the movie would have been in for a nasty shock though!
In his humanoid mode, Marbles fares about as well as his face. Which is to say not great but with a charming ugliness about it. His skinny arms are welded to big flat flaps of rock which swing from side to side, and because of this he ends up looking really tubby.
Because of the way his arms are constructed, there isn't as much motion as there should be because the flaps end up scraping against everything. He does have a decent amount of die-cast in his arms and legs though, and the bright green is at least striking if (again) a bit ugly.
In the cartoon, Marbles had a boomerang as his weapon. The toy comes with a double-barrelled gun. There's no way he could hold a boomerang, and no other figures that come with a boomerang, so I have no idea what happened there. Interestingly it is held in with two pegs, that straddle around the arm and peg straight into the arm flaps. Unfortunately the grey of the gun tends to blend into the grey of his rock.
Marbles' transformation is half nice, half frustrating. His legs fold neatly up, and his head swings forwards into an amusingly shaped groove on his chest. The problem is that his arm flaps are very hard to properly manoeuvre into position given how tightly it locks together.
As a rock, Marbles could have been better. He's clearly got legs that are folded up, with no effort made to hide the gap between them or their general shape, though some angles are better than others. He has a slight marbled effect, but not particularly stunning and ends up being very grey.
It's hard to get that enthused about Marbles. He's a bit frustrating as a figure, and lime green and grey aren't a great colour combination. It's also surprisingly difficult to get one in good condition, as he seems especially prone to paint chipping and rust. That said, his really weird head is worth the price of admission alone.