In the following context the plural of life is "lifes". Is it an acceptable plural for life? If yes, when can we use it?
The Royal Academy advocated a style that was typically staid and relied heavily upon the use of dark amber and brown tones to depict overly idealized landscapes, carefully arranged family portraits and still lifes, and overly dramatic nature scenes such as boats caught in stormy seas.
It is the plural of 'still life', a type of painting, and is acceptable.