Titan Bird

Titan birds are symbiotic flying organisms native to Saturn's moon Titan. They are a migratory symbiosis of silane lilies and CHON sponges, which spend most of their life cycles as separate organisms.

Anatomy and Physiology
Titan birds resemble blocks of ice with wings. The wings span 10 to 15 meters (33 to 50 feet) and are black with an oily sheen. The wings are said to move in a fashion distinctly different from any terrestrial animal. The wings are the silane component of the creature, while the icy body is the frozen CHON sponge. The CHON sponge provides direction and a measure of intelligence to the the symbiotic creature.

Biochemistry
Titan birds are a merger of two completely different biochemistries - silane, which is a form of silicon-based biochemistry, and CHON (carbon, hydrogen, oxygen, nitrogen), which is the same biochemistry found on Earth. The biochemistry of the Titanian CHON sponge is only marginally different than that of Earth life, using all the same elements and water as a solvent. The silane component, however, is based on silicon-hydrogen bonds - silanes - and is suited to very low temperatures. The silane component uses liquid methane and ethane as a solvent instead of liquid water.

It is implied that neither of these biochemistries naturally emerged on Titan, and that they instead arrived on the moon via panspermia. CHON biology is thought to have come from Earth or Mars, while silane biology most likely originated in the liquid nitrogen lakes of Neptune's moon Triton.

Diet
The silane lilies are plantlike when not part of a Titan bird and feed through photosynthesis. It is unknown how CHON sponges feed when they are separate.

When united, Titan birds demonstrate predatory behaviors, suggesting that they are carnivores in this state. They attack and down a human-piloted craft when it first arrives on Titan, evidently mistaking it for food.

Reproduction and Life Cycle
Silane lilies and CHON sponges apparently reproduce while separate, using unknown means. Their union is part of a seasonal migration, allowing silane lilies to reach hydrocarbon lakes and CHON sponges to reach Titan's rare patches of liquid water.