Bot-spiders (also simply bot-parasites) are amoeba-like organic-technological parasites, and one of the few forms of Cybertronic wildlife known to feed of Transformers.
Bot-spiders may appear inert, blending in with their surroundings until a suitable prey approaches. They then swarm, descending en masse to feed on the victim. Though individually fragile, large numbers of the parasites can overwhelm most transformers, eventually resulting in death. The bot-spiders then appear to cocoon their victims in a coral or fungus-like growth until they reach mummified state. The proses can cause exo-structural bleaching, giving the shells a ghostly age-whitened appearances.
While pursuing the Decepticon Thrust through Cybertron's lower levels, Starscream and several others passed through the Unicron-Cybertron warp-gate into Unicron's depths where the encountered the cocooned remains of the bot-spiders' victims or victims.
Sideways commanded the concealed bot-spiders to attack them, then left, trusting the parasites to finish them off. But all parties were able to escape, either by quickly fleeing or by systematically whittling down the swarm's numbers until free of them.