The Obsidian Deeps is a black and lightless void in a remote section of space. As a means of adapting to the lightless void, the inhabitants of the Deeps have evolved an advanced sense of hearing, while at the same time losing their sense of sight.

Among the blind creatures of the Deeps was Rot Lop Fan a brave and noble member of his people and an ideal candidate for the Green Lantern Corps. Rot Lop Fan was approached by Katma Tui to join the Corps and serve as a Green Lantern however her request was meaningless to the blind alien.

Being blind, Rot Lop Fan had no concept of light or color. The terms "green" and "lantern" had no meaning to him, and could not be translated by the power ring.

The resourceful Katma Tui reasoned that if she could not explain the concepts of light, she would translate using sound. She instructed Rot Lop Fan to imagine a sound with a pleasing resonance. This he did, as a sound in the F-Sharp range. With the concept of sound, Rot Lop Fan could manipulate the energy of the power ring. Rot Lop Fan was overjoyed and accepted the commission into the Corps.

Katma Tui modified Rot Lop Fan’s uniform to reflect a bell insignia on his chest and welcomed him into the "F-Sharp Bell Corps." His ring has also adopted the appearance of a bell, which Rot Lop Fan uses with great effectiveness.

Rot Lop Fan served during the Crisis on Infinite Earths and was present on Oa when the Guardians left our plane of existence. After the first destruction of the Central Power Battery, Rot Lop Fan was seen briefly in an alien bar during Kyle Rayner’s encounter with another depowered Lantern, Adara.

Some time later, Rot Lop Fan was one of the many former Green Lanterns who were freed by Guy Gardner from an interstellar slave ring. He has since resumed his duties as a Green Lantern following the rebirth of the Corps.