Short answers, pulled from the story.
Conglomerate is a sedimentary rock made up of rounded gravel-sized clasts surrounded by a finer-grained matrix of sand, silt, or clay. The clasts and matrix are cemented together by calcium carbonate, iron oxide, silica, or hardened clay. The rock must contain at least 30 percent of rounded to subangular clasts larger than 2 mm in diameter.
Conglomerate forms when rounded gravels deposited by water or glaciers become solidified and cemented by pressure over time. The environments of formation include rivers, alluvial fans, shallow and deep marine settings, and glacial deposits.
Conglomerate contains rounded to subrounded clasts, while breccia contains angular clasts. When a rock holds a mixture of both rounded and angular gravel clasts, it is sometimes called breccio-conglomerate.
A fanglomerate is a poorly sorted, matrix-rich conglomerate that originated as debris flows on alluvial fans, typically in rapidly eroding desert environments. Fanglomerates are thought to contain the largest accumulations of gravel in the geologic record.
Conglomerate was found on Mars at an outcrop named Hottah, discovered by NASA's Mars rover Curiosity. The gravels ranged from sand-particle size to golf-ball size and were interpreted as having been deposited by an ancient stream that flowed at walking pace and was ankle- to hip-deep.
Notable examples include the cliffs at Montserrat near Barcelona, where the rock gives the mountain its name meaning "jagged mountain" and was used to build the Santa Maria de Montserrat Abbey; the Crestone Conglomerate at the foot of the Sangre de Cristo Range in Colorado; and the Copper Harbor Conglomerate found on the Keweenaw Peninsula and at Isle Royale National Park in Lake Superior. Dunnottar Castle in Scotland sits on a conglomerate promontory jutting into the North Sea.