"Basically, he was like a merman...one who lived in a volcano..." (Continued)
While his mother had been sitting on her customary rock formation within the magma pool, Moturi had been bobbing up and down, allowing the motion of the molten surface to keep him afloat. "Yes, Trima," he said ("mother" in their tongue). "I was planning on visiting her, maybe taking her out for a dip in the warmer flows.
His mother looked at her son, watched him move within the lava. He was thin, but powerfully built for his young age. His onyx flesh glinted in the copper glow of the caldera. He had whipcords for "hair" that extended from his forehead, in a vertical, straight line fashion, to his hips. A bubble of lava to his left popped, showering his head with molten bits. He didn't bother raising his arms to brush the magma from his head. He simply shook, sending the bits back into the pool. "I'm sure she'd appreciate that."
"Well, Trima, I'm off, he said.
"See if you can bring home a rocegar on your way back."
He nodded his ascent, and at that, he allowed himself to drop into the magma. First, he used his arms in a sweeping motion, which displaced the lava, allowing him to drop within the caldera. When he got to a depth of about 100 meters, he rotated his body downwards in a position where he could use his legs.
His lower limbs could be "locked" together, functioning as a single muscular appendage (which is why, at times, his species looks similar to that of a mermaid), or move separately allowing him bipedal movement. "Swimming" through lava was a much less graceful affair than it was through water.
