Six-legged oxygen-breathing symbiote/parasite with the ability to meld itself to a wide variety of lifeforms.
Individual Melders resemble a fleshy, hairless six-legged spider about the size of a large baseline human hand. They attach themselves to the back of the skull and insert a cluster of tendrils into the brain and circulatory system of their host. At this point the Melder's internal organs begin to atrophy and are replaced by new neural tissue.
When a baseline or near-baseline human experiences this process they develop an enormously enhanced ability to calculate probabilities, project trends and juggle large numbers of multiple variables in their heads. A modosophont melded in this way has an enhanced ability to predict the future, given enough data; some observers liken this to the mythical ability known as precognition. Melders are rarely used except by certain ai-phobic factions and biotech enthusiasts.
Although their origins are not certain, it seems likely that the Melder is a biotech augmentation device originally created on Arcadia many millennia ago, as it shows distinct similarities in cytoplasmic microstructure to other Arcadian implants and symbionts.