Gromia is a widespread genus of marine and freshwater amoeboids, closely resembling some foraminiferans. It produces an organic test, which is ovoid or lobed and may exceed one millimetre in size; this resembles a small grape, in that its centre is fluid-filled but lacks organic matter, which is concentrated in its translucent test and underlying sediment, making the organism almost neutrally buoyant. Filose pseudopods emerge from a single opening in the test.