Does it have a rhizome? It looks like it an Anubia species. If so, you don't want to bury the rhizome, only the roots! The rhizome is the thick stem that the leaves attach to. Imagine the leaf above, the leaf stem coming down, the rhizome runs left to right, and the roots grow down. It should have some roots growing from it too. If you bury the rhizome, the plant will begin to look terrible.