Reefs are built by _____, tiny, soft-bodied animals related to jeyllyfish.
coral polyps
fish
sea horses
starfish
Coral reefs are _____ when people take coral from the reef to make things.
protected
built up
helped
damaged
Global warming has caused many reefs to become ____.
bigger
healthy
better
sick
If we take care of reefs, they can _____ or come back.
break
die
tear down
rebuild
