Lithops

Origin

From the genus name.

Full definition of lithops

Noun

1. Any of the genus of succulent plants resembling stones.
• 2008, January 3, Anne Raver, No Need to Fly South to See Blossoms in Winter, And the succulents house, which is kept a cool 60 degrees during the day and 50 to 55 degrees at night, holds aloes and lithops (which look like small stones), just beginning to bloom.