This is a crust of the naturally occurring salts in the water. Clay is porous and as water moves from the wet inside to outside and evaporates the salts are left behind.
They can be removed with a scrub brush soaked in vinegar.
The Ficus benjamina (probably "Starlight" cultivar) does not look well but might grow new leaves.
It looks over watered. Is there drainage in the pot?
I suggest you repot into a different container with drainage holes, because, yes, the soil looks wet.
The other thing is, I can see white insects, but can't tell what they are - there are a couple hiding under the dead leaves, plus another on the side of the pot in the photo. They might be leafhoppers, but I'm only guessing... which might mean your plant needs spraying with at least neem oil, although it would be better to ID the insects. On the other hand, they could be associated with the dank, wet soil conditions, hard to say.