Gathering coils were engineered biotech weapons, described as a "semi-species" by the Thirteenth Doctor.
These coils resembled cables and wires of various sizes, acting like tentacles, which could gather data. At least some coils also had the ability to plant DNA bombs. A number of Gathering Coils were able to gather to create one large, more polyvalent creature, though such a swarm could be deactivated with a large electric shock.
Tzim-Sha used one such swarm in order to locate a trophy to take back to his planet, despite this being against his species' rules. It was later deactivated by Grace O'Brien who electrocuted it with a cable at the cost of her life. (TV: The Woman Who Fell to Earth)