White Spots On Lava Rock

Are the spots/growths a bit fluffy? I'm thinking possibly fungal growths.
Where did you get the rock from? And was the plant already attached?
I've never used that sort of stone in my tanks, so I'm not sure what to expect from it, but as it is very textured I'd have thought it would be easy for things to get into all the holes.

Yes, a bit fluffy, I was thinking fungal growth.  Just not sure if it is nasty or not.
I got it and the plant from Aqua Essentials, they were not attached when I bought them.  It's a Microsorum pteropus Windelov.  It grows well on lava rock apparently.

Would hope there is nothing animal abut it - nothing animal in the tank yet!

Will do, thanks Littlefish.

You may have to remove the plant to be able to treat the stone separately.
I'd suggest waiting to see what the supplier suggests, as they are the experts on this sort of thing.

You may also want to be quite careful with this rock when your tank is up an running, especially if you are considering corys as mentioned. The rock is quite rough, which may damage the barbels of the corys if they spend a lot of time going over it looking for food. You may have the same issue with your gravel substrate, if it is rough/sharp gravel. Some of the aquarium gravel has more rounded edges, which is probably better.

I have sand in all my tanks, but some of the others may be able to give more advice on how other/mixed substrates work with corys.

It may be worth getting a cheap toothbrush to give the rock a scrub in a separate container of water. Get rid of as much as possible and try to keep the growths under control.