Today I visited what is perhaps the most unique nature preserve in the galaxy. Dave-3 (curse you, international star registry!), the planet for which the biodiversity can fluctuate significant percentages if a tourist shows up with lice or a particularly lively digestive tract. This is because, aside from the small airtight sphere that makes up the observing station, Dave-3 is home to a single (known) organism.
I didn't know this when I first landed. I was on a summer space-trip across Galaga-Australis and decided I needed a break from the space lanes and stopped at this little tourist spot. At first I wasn't really sure what the deal was with the place (not fond of visitor's handbooks) so it was a bit confusing. I stepped out of the airlock into the observation sphere, and spent several moments staring puzzled at a small pit in the ground just below the sphere, in which crawled a small insect like creature. Finally I asked the sole guide (and seemingly the only staffer on the station) "What is that thing?" "Why," she replied in an artificially peppy and wistful voice, "that's Xandalor! The World Eater!"
I glanced around a bit then finally noticed the plain black text printed on the glass of the sphere "Xandalor, The World Eater!"
"Well then." I replied. "Thank you." "Oh of course sir, let me know if you need anything."
I returned to lending my puzzled attention to Xandalor for a few minutes, watching him (it?) scuttle around in his small pit in the lifeless dirt of Dave-3, then I realized if I wanted to get to the bottom of this anytime soon, I had better read the visitor's guide.
Apparently Xandalor the World Eater was the greatest accomplishment of the great bio-engineer Ernest Hostenbrau, who I had never heard of before. Xandalor had a few very special and unique abilities. First off, Xandalor's digestive system is 100% efficient, turning absolutely everything it consumes into useful energy or bodily resources with no waste whatsoever. Secondly, Xandalor's stomach/mandible/asophagus hybrid kinda thing is lined with a number of very efficient digestive... things. Which, beside being able to grind down nearly all elements and compounds, can also secrete a wide variety of acids, amalgams, and other chemicals, to aid in the digestion of whatever it is Xandalor is eating at the time. Worlds, one would presume. Xandalor possesses an incredibly strong exoskeleton that is allegedly the greatest single work of bioengineering in the galaxy, and the ability to survive in vacuum, and of course, extreme temperatures. Also, Xandalor is biologically immortal
Apparently Xandalor was meant to be a proof of concept for some ongoing project of the great, late, Dr. Ernest Hostenbrau, before he tragically lost his mind and jumped out a window, apprently just after completing a great essay on the power and greatness of himself, and his wonderful creation, Xandalor, the World Eater.
No one nearby was particularly interested in poor Xandalor or his unique properties, but apparently there was some interest locally in testing the Dr.'s grandiose claims about his creation, so the World Eater was brought to a small, uninteresting planet orbiting a small out of the way star named Dave, and ever since, has been slowly eating worlds. One bite at a time.