Lump of brain

"For some reason, you feel a terrible sense of loss as you look at this familiar lump of gray matter."

- in-game message

Lump of brain is an item in the Fallout 3 add-on Point Lookout.

Characteristics
It is a piece of the Lone Wanderer's own brain preserved in a glass jar which was removed by Tobar during Walking With Spirits.

Location
The item is in the engine room of the Duchess Gambit, on the table next to Tobar. It can only be obtained after completing the quest Walking with Spirits and asking Nadine in the Ark & Dove Cathedral to remove your scar.