Ah, I thank you for asking. In actuality, they are humanoid. They stand at around ten feet in height, and have a considerable amount of heft to them. Their heads, however, are almost comically small, being only slightly bigger than a fully grown human. In actuality, they simply look like large and plump Humans, save for their vibrant shades of green, red, or even blue skin. Their horns would sprout from the very top of their heads, and curve backwards, eventually going into their heads. The Dwarves created Spires, devices that go through the head of a Ryaa, and act as an artificial brain.

[url=https://vignette1.wikia.nocookie.net/finalfantasy/images/a/ae/Cuchulainn_RW.png/revision/latest?cb=20120702194736]Here[/url] is an image that I had found that can serve as a rough reference.