Trawling was an umbrella term for a variety of neural imaging technologies which allowed memories -- and in some cases even thoughts -- to be scanned, then examined and/or implanted into another. Even on the relatively primitive human colony of Sky's Edge, trawling technology could be acquired by both government and underworld entities. The grubs possessed a similar capability, as seen during first contact between them and humanity. However, it appeared to require the grub to consume the individuals whose memories were desired.