Fishlegs can look past this Catastrophic Quaken's hard exterior, and see her softer side. He just has to look very, very hard.
Spikeback has a pudgy body that is deep purple in color. Unlike most Quakens that have brown or darker colors, Spikeback has glistening, crystal-like spikes that jut out of his back. She has several brown spots on her chin, wings and limbs.
There are giant spikes of crystals on Spikeback's stone slab in Rise of Berk.
Spikeback is the only Premium Dragon to be added to Rise of Berk before her species was made available in game, in her case, the Catastrophic Quaken. However, she is not the only dragon to have this distinction, as Muddlehunt appeared in Rise of Berk before his species, the Gobsucker, did. Sleuther also appeared in Rise of Berk before his species, the Triple Stryke, did.