There is a point in the development of most planets where most of their surface, and a lot of the space beneath, is urbanized. Some material — usually a metal — is more common than grass, and the trouble with a working photosynthesis and cellular respiration relationship is cleverly worked around to cram in more homes, more towers and skyscrapers and warehouses. Not much wildlife survives the relatively rapid progress of this urbanization event horizon, but what does, does so admirably. The phenomenon of unrelated interplanetary evolution is called bottlenecking, where the progression of civilization forces changes on the world, creating patterns visible in an interplanetary study, given time.
One such species that proves its resilience time and time again is the ferrospider. Its coloration spans all the colors of the color-blind spectrum. Size varies depending on the exact path of development the planet takes, but, save for a handful of notable exceptions, ferrospiders tend to be only slightly larger than their average twenty-first-century spider ancestors; from four to ten inches in body length (11 to 25 centimeters), and six to twelve in width(15 to 30 in centimeters). They are usually, but not always, of the tangle-web spider family, their weaving more for defense than prey-catching, especially among the smaller members of the ferrospider macrospecies. As such, most ferrospiders have developed extremely complex maze weaving patterns, and have been noted to be intelligent enough to adapt web designs to take advantage of the surrounding area. Most ferrospiders are not known to be social spiders, yet there have been documented reports of webs over half a cubic kilometer in size.
Of particular note is the typical ferrospider-silk composition, it being the primary contribution to their name. Metal is part of the silk protein’s chemical formula – usually iron, but instances of copper, led, and even silver have been observed – resulting in loss of elasticity and stickiness, but a sharp rise in durability. Most ferrospiders tend to be scavengers in nature, searching for metal parts to add to their web.
As is the case with most post-planetary urbanization survivors, ferrospiders tend to rely moderately-to-heavily on some sort of symbiotic relationship. A common example is food processing – often times a ferrospider will purposely uncover the metal core of its webs to form a habitat for some kind of ferrophage plant or fungus, and instead of struggling to consume raw metal, they feed on the plant’s processed excretion – the content the spider needs is what the plant considers waste.
The largest documented evolution of a ferrospider is two and a half meters in length, almost three in width. Its massive webs are what have gained this ferrospider its title – mazeweaver. The spider lives within a maze of woven metal tubes, with the sole intent to confuse and trap intruders. Like most spiders, the ferrospider is able to secrete more than one form of web. Aside from its basic metallic web, used for structural support, it can spin extremely sticky variant, and a substance identical to its structural web in appearance, but which is extremely fragile. It is believed that all ferrospiders have an intrinsic awareness of their entire web, or that they somehow incorporate a chemical or pheromone into their webs unique to them. The mazeweaver is thought to be either extinct or endangered, extensively hunted for its disruptive weaving behavior.
Planetary urbanization forces creatures to live together, restructuring the relationships of prey and predator to prevent extinction. Often times these bonds are formed in response to the threat of humans, or their machines – there have been insects who have evolved to live in the scorching innards of supercomputers and industrial equipment.