@SegiDream and @Chickstarrs
yes, you're right about the Anubias. I mixed it up with crypts. Oops.
Anubias will sometimes grow proper roots from the rhizome into dirt or gravel (I have one that did), while Java fern only ever grows the brown stringy things. But you are right, both Anubias and Java Fern have rhizomes that need stay out of the dirt and gravel.
yes, you're right about the Anubias. I mixed it up with crypts. Oops.

Anubias will sometimes grow proper roots from the rhizome into dirt or gravel (I have one that did), while Java fern only ever grows the brown stringy things. But you are right, both Anubias and Java Fern have rhizomes that need stay out of the dirt and gravel.