Ice worms

Ice worms are blue-hued creatures native to the icy climes of Serpent Isle. They appear in Ultima VII Part Two.

Description
Ice worms may be found on the cold plains of the north lands, where they roam the ice fields in search of prey. While they are possessed of an aggressive temperament, these beasts are easily dispatched by a prepared explorer and are frequently hunted for their hearts, which act as a magical reagent in numerous ice spells.

White Worms
On the frozen world of Anodunos there exists a race of blue-skinned predatory worms known as "white worms." These creatures bear obvious similarity to the ice worms of Serpent Isle, although it is unknown if any link exists between them.

Trivia

 * The need for nine worm hearts late in the game to create the soul prisms can hit players unprepared - especially when using the Ring of Reagents. Since they can't be bought any longer (due to Pothos being dead), it often results in a frustrating hunt for ice worms on the Ice Plains.