>>5019103
Asked it for a turtle in 1 billion years:
Glacioscutum siphonax - “ice-plated siphon turtle”
By this time, Earth’s climate is swinging violently between extremes. As the sun brightens, the planet’s orbital and axial changes trigger frequent hyper-glacial periods. Most surface life clings to equatorial refuges or sub-ice ecosystems. But turtles - absurdly resilient survivors - have taken an unexpected path.
Glacioscutum is a descendant of softshell turtles that colonized geothermal fissure lakes under ancient polar ice. It's now a deep-subglacial aquatic specialist. Around 1.8 meters long, it has a broad, semi-transparent carapace with embedded antifreeze glands and bio-optic cells to absorb faint geothermal light.
The skull is elongated with a retractable siphon snout - used to inhale warm, mineral-rich microbe plumes from hydrothermal vents. Jaws are adapted to filter mats of extremophilic bacteria and sulfuric biofilms. The limbs have become paddle-like and end in cartilaginous hooks for anchoring against currents.
It breathes both through lungs and highly vascularized throat tissue - a holdover from earlier aquatic turtles - and can enter torpor for months during energy shortages.
Behaviorally, it’s solitary, slow-breeding, and shows minimal learning capacity - but its biological efficiency is unmatched. Eggs are laid in silica-crust domes near warm fissures and left to incubate in geothermal heat.
Glacioscutum has no eyes. Instead, it detects pressure, temperature, and faint bioelectric fields. Its only real predator is a blind, eel-like scavenger that tears open weakened shells during nutrient crashes.
Despite a billion years of change, this turtle remains what it always was: a quiet, cold-blooded survivor. Shelled, slow, and eternal.