Complex sentence: Calved from the Ross Ice Shelf of Antarctica near Roosevelt Island in March 2000, B-15 broke up into several pieces in 2000,2002 and 2003, the largest of which, B-15A, covered 6,400 km² of the sea surface.
Split into simpler sentences: Calved from the Ross Ice Shelf of Antarctica in March 2000, Iceberg B-15 broke up into smaller icebergs, the largest of which was named Iceberg B-15A. In 2000,2002, and 2003, Iceberg B-15 broke up into several pieces, the largest of which, B-15A, covered 6,400 km² of the sea surface.