Gromia's a widespread genus of marine and freshwater amoeboids, closely resembling some foraminiferans. It produces an organic test, which's ovoid or lobed and may exceed one millimetre in size; this resembles a small grape, in that its centre's fluid-filled but lacks organic matter, which's concentrated in its translucent test and underlying sediment, making the organism almost neutrally buoyant. Gromia sphaerica's a large amoeboid discovered in the Arabian Sea.… (More on Gromia)