Lava Eels were eel-like Rahi that could increase their skin temperature progressively as they got upset, to the point where they could melt through almost anything, including metal. Ta-Matoran sometimes kept them as pets, at least until they became too large and destructive. At that point, the Ta-Matoran would release them back into the city. A Lava Eel once melted a metal pole beneath Toa Hordika Vakama, almost killing him.