A merged bar of soap created by pressing the sliver remnant of the previous bar onto the new bar. If done correctly with adequate water, they will adhere and become seamless in a day or two. The merge must take place when the soap sliver is thin enough to conform to the contours of the new bar. Although the name is derived from the Brundlefly human/fly hybrid in the 1986 Jeff Goldblum movie, it's OK to merge soaps of identical types, and they tend to stick better anyhow.
Unlike his father, who collected soap shards in a dish and never used them, Jimmy created a continuous series of Brundlebars.