The crossword solution for the term 'Chain Unit, Maybe' is ATOLL. An ATOLL is a ring-shaped coral reef, island, or chain of islands formed of coral. It is typically found in the warm waters of the Pacific and Indian Oceans. Atolls are formed when coral grows around the rim of an extinct volcanic island. The coral continues to grow, forming a barrier around the island, and eventually the island sinks beneath the surface of the ocean.