Well, just twist them out and be gentle as you can, shaking and giggling them loose slowly.

Give it a few minutes of doing this, they will be in there good.
They are from Rivers, so they need to keep from getting washed away, which iswhy they and Crypts often have massive roots, and then the rivers drop their levels and they are left high and dry.

Large roots imply nothing that they prefer nutrients in either location however(sediments), but that's what everyone seems to like to claim.

However, adding sediment ferts to stem plants also does the same general effect

So you could make the claim for all plants. Making these no different.

Regards,
Tom Barr