Do not engage in any form of purchasing of coral souvenirs. You shouldn't take anything from the ocean, alive or dead. By taking the corals from the ocean you also encourage the loss of lives in the ocean. It is illegal to sell coral in some countries. Coral can take a long time to grow, so taking it for your aquarium or jewelry box can have a lasting effect that will take years to undo. Red and pink coral is especially prized as jewelry because of its coloring. It comes from deeper waters. 
Don't purchase coral reef fish, either. Inquire about marine fish before you buy them in pet stores. You want fish that were bred in captivity.