Assuming it covers the entire floor, a carpet is une moquette. If it only covers a portion of the floor, it is un tapis.
sand (sometimes shells)
The mantle
rug
Desert pavement
rug or mat
Little undergrowth in deep shade.
the border
The abyssal plain.
neritic is near shore an covers about 1/4 of the ocean floor and pelagic is deep ocean basin and covers the other 3/4 of the ocean floor
No, there isn't sand on the floor of the colosseum because there is no floor. What was once was the floor is gone. When you visit it you look down into what was under the floor originally. When the Romans used the colosseum they could flood the floor to have sea battles.
its covered with rock and stones