What can secrete an exoskeleton that builds up to become a reef?
graptolites some invertebrates remains of prehistoric life humans insects gastropod shells barnacles all invertebrates
A B C D E F G H
Corals, and invertebrates in general, are delicate creatures.
some invertebrates secrete an exoskeleton that builds up to become a reef
What can secrete an exoskeleton that builds up to become a reef? (A) graptolites (B) some invertebrates (C) remains of prehistoric life (D) humans (E) insects (F) gastropod shells (G) barnacles (H) all invertebrates