This is one of the many incredible images highlighted in National Geographic’s feature story entitled, “Unseen Titanic“. The story first appeared in the April edition of National Geographic magazine and is now available online.

In this underwater photo we see two of Titanic’s engines lying exposed in a gaping cross section of the stern. They are draped in “rusticles”—orange stalactites created by iron-eating bacteria. It’s remarkable to imagine these massive structures, four stories tall, once powering the largest moving man-made object on Earth.