Marilyn Chambers, the pretty Ivory Snow soap girl who helped bring hard-core adult films into the mainstream consciousness when she starred in the explicit 1972 movie "Behind the Green Door," has died at 56.

The cause of death was not immediately known. A family friend, Peggy McGinn, said Chambers' 17-year-old daughter found the actress' body Sunday night. Chambers was pronounced dead at the scene, the county coroner's office said Monday.

Chambers and fellow actresses Linda Lovelace and Georgina…