This category includes pebbles, cobbles and boulders. They prefer using rounded pebbles to jagged rocks. Projectiles used in hand cannons were known to include rocks, pebbles, and arrows. Hence, protection from rocks, pebbles, and hard, uneven surfaces is lacking. The first pottery was made of thick clay mixed with pebbles, shells or plants. Its original style of usage was by lines drawn in sand with pebbles. Some courtyards were paved with quartz pebbles or broken pottery. He also oversaw the DVD commentaries of "The Sand Pebbles" and "Executive Suite". Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. McQueen received an Academy Award nomination for his role in "The Sand Pebbles". It has a strongly weathered surface covered with cemented faceted pebbles. The Rock Pikmin take on the form of small polished pebbles, rather than plants. A rotating drum causes friction and attrition between rock pebbles and ore particles. Fred is the husband of Wilma Flintstone and father of Pebbles Flintstone. A rock made predominantly of pebbles is termed a conglomerate.