Conus cyanostoma is a species of sea snail, a marine gastropod mollusk in the family Conidae, the cone snails and their allies.
Like all species within the genus Conus, these snails are predatory and venomous. They are capable of "stinging" humans, therefore live ones should be handled carefully or not at all.
The size of the shell varies between 17 mm and 32 mm.
This marine species occurs in the tropical Indo-Pacific Region and off Australia (New South Wales, Queensland).
