Sentence:  Inside its exhibit hall, behind panes of glass, in a white-lit lab, a team of restorers works on an ancient Byzantine floor: 44 square yards of stone <WSD>shards</WSD> rescued from Lot's Cave Monastery. 
Meaning of the word marked with <WSD> tags:  A piece of material, especially rock and similar materials, reminding of a broken piece of glass or pottery.