This is part six of Blue Ice. Anton deGama is in the rings of Saturn, planting bio-engineered plants on a chunk of ring ice, when his colleague Kellerman sees something blue moving on the ice. Despite all common sense, Anton moves towards it, to see living creatures moving towards him...
Each creature was shaped like a snowflake hexagon atop a crystalline frond. The six panels could change their attitude independently, to grab sunlight and to focus it through the crude crystal lens at the base of the frond. The thing moved by directing the faint sunlight through the organic lens onto the ice below it: as the ice burned away, the spreading water-vapour pushed the creature onwards. It obviously relied on the marginal gravity of the fragment to keep it from drifting off into space.
Anton suspected the creatures were not greatly dissimilar to the draxbloom or svenskite plants that ringfarmers cultivated, clearly formed from the same silicorganic genetics. But Anton had never heard of anyone bio-engineering anything like this.
Kellerman was demanding that he reply. He finally murmured "They're alive, Kellerman."
"I was beginning to wonder if you were, Anton! What are alive?"
Anton briefly described what he could see, watching the creatures devouring his crop. Each one enfolded a draxbloom in its snowflake. The motion was so slow and sensual that Anton for a brief, delirious moment wondered if this was some bizarre mating ritual. But then he saw the flower petals shattering and the fragments being absorbed. This was a ritual of consumption, not reproduction.
As always, comments appreciated!