It looked like a stone drifting, about 30 centimeters long, stonish, white and light brown patterned. It swam just in front of me. When i turned around, after passing it, it seemed to swim away backwards. I say friendly because it returned to me and then i could see octopus like extensions, whitish, with which it propelled itself.

Later i was told about its poisonous spikes. It uses those only when attacked and there was nothing like that happening. More a felt connection, i really liked the animal and felt this reciprocated.