The Seishin Seishin no Mi (Spirit Spirit Fruit) is a Paramecia Type that allows it's user, Darwin Delfo, to leave his physical body and turn into a ghost. In ghost form, he cannot be seen by anyone who can't use Observation Haki and is intangible, and it seems that he can't be affected by Armament Haki. Darwin can also create clones of himself that have the same thought patterns as Darwin. He can also possess people in Ghost Form. The drawback of this fruit is that the user's regular body is still open to attacks, but Darwin can create a ghost clone and then have that clone control his regular body.
In terms of design, it is white with a yellow stem.