Possible Clues:

• It's hard to abandon singing the praises of certain islands
• Pink marine substance
• It grows in water, in a manner of speaking, after a century
• Deep pink colour
• Snorkeling milieu
• Pink growth which forms reefs and islands
• Carol (anag.)
• Calcareous skeletal remains forming reefs
• Reef composition
• Shakespeare: 'Full fathom five thy father lies, of his bones are . . . . . made'