They certainly do have a world of expressions in their eyes alone.
The "green tofu iguana cubes" are made by Nature Zone, they are called Iguana Bites
http://www.naturezonepet.com/samples.html they apparently give out free samples. She just loves them.
When I am out of fresh greens I use a mixture of Mazuri Iguana Diet, Iguana Cubes, and Monster Iguana Diet all together. The mixture of all three has increased her appetite. She was a rescue, her skin was almost black when we picked her up and she was underweight and she was missing a few toenails. Her spines have been starting to grow back too. She loves the fresh greens, but goes crazy for this mixture. I have seen her jump across the cage to get to the plate faster.