A silicon based possibility:
Centipedelike, with a translucent caripice and many metal studded legs.
--> Common window glass is somewhat translucent to infrared light. Aerogel is a world record holding insulator against heat. Both are silica materials.
--> Some sea creatures have been shown to excrete metal in the formation of their caripices - others have been shown to excrete glass.
It maintains a tremendously high internal temperature, required to keep it's metabolism running. It's back has hundreds of thousands of articulated spikes, each made of dead cells. The creature can wave these spikes in defense, or in the air for cooling by moving blood through them, or into hot puddles of molten metals or other high temperature liquids that abound in it's world, to warm itself.
--> Fins have been used with great success on Earth for temperature control in animals and in machines, both for heating and for cooling.
Since much of it's internals are wrapped in natural aerogel-like material and it's hide is resistant to infrared radiation (which includes loss), loss of these spikes is a danger. Thus, much like a shark's teeth, new spikes are constantly in development and click into place over the muscle that controls their movement (and flow of fluid through them) as old ones break off and are discarded.
--> Sharks and shark teeth and the physiology of their gums and nerves.
The creature does eat, although a human wouldn't recognize it as such. The creature's digestive tract is little more than a long tube with millions of hairs adorning it. As it inhales, the organic debris that always falls upon it's world from his dense atmosphere above gets trapped. The creature then digests the material on these hairlike threads, before ejecting the waste in the next breath.
--> Venus is a case of runaway greenhouse that could cause temperatures like this (actually, much higher temperatures, but I digress). There are organics in it's atmosphere. They might rain out. We don't talk about the world much, so you could easily device an ecosystem where creatures live in the upper atmosphere, then eventually die and rain down.
--> Filtering for food is a common feature of animals on Earth.
--> Digestion of those materials on the threads is found in the Sundew plant and other flora and fauna.
--> At first sight a human would not see this creature "eat" nor "excrete", nor if it was intelligent enough that we encountered it as a sentient being, would we have the opportunity to say, shove our hand down it's mouth or check for waste products. Would we even clearly know which end was which?
The creature's mode of travel is similar to centipedes on earth - a continuous ripple effect. Each metal leg is attached to a bladder that is in turn surrounded by muscle. the bladders are temperature controlled by a surrounding of aerogel and veins running outside the bladder, as well as by an extention of the leg that can move inside the bladder.
The creature warms the bladder with the surrounding veins, causing the bladder to swell, and pushing the leg forward. It then releases a sheath of aerogel from around the extention of the leg, which causes that extention (and then the leg itself) to warm. This radiates heat from the bladder, causing it to cool and the muscle to contract, pulling the leg forward. This causes the sheath to close around the leg extention, and the internal fluid again starts to warm the bladder.
The curious result is that the creature has no proper way to stop moving, and so from it's birth onwards, moves.
--> The science is sound... enough. You could make a case that there wouldn't be enough strength in the contracting or expanding bladder, but we really don't know it's entire physiology. This works, imho.
The creature mates by filling one of it's spines, which also triple as penises, with semen until pressure causes it to erupt, firing it at another creature. If the spine penetrates the other creature, the semen find the reproductive organs.
--> Snails. Yeah, this happens, and much worse. Snails are psycho.
The creature protects itself by wrapping and rolling itself into a ball of spikes. It then waits for the predator to go away. Now that it's sentient, it can of course, use a weapon. But it still has the instinct to roll in a stressful situation. Those that do not, become leaders.
--> Millipedes, armadillos, some caterpillars...
This is all just a thought; a fun thinking activity. It may contain errors, but is probably a fairly sound concept overall. I have added this proviso because apparently I didn't the first time and people thought I was dictating what had to be and that I had planned out the entire biology and habitat of this creature in advance. I didn't. Enjoy!
