Eggshells

Eggshells is a 1969 American independent experimental film directed by Tobe Hooper in his directorial debut. Hooper, who co-wrote the film with Kim Henkel, also served as one of the film's producers. The film centers on a commune of young hippies, who slowly become aware of an otherworldly presence that resides in the basement.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.