What is the white substance crystallizing on my whetstone, and how do I remove it? the stone lives in a wooden box and started developing these crystals on the corners and sides and is growing up to the flat side where the sharpening is done.

What type or brand of stone is this? Do you wet your stone with water or oil? I use Japanese synthetic whetstones with water and have noticed this before on mine. The only time it occurred for me was when I didn't let the stone dry completely before storing away. I tend to soak my stones for several minutes before use so it gets pretty saturated. I removed the crystals by reconditioning the stone with my diamond stone. Afterwards, I let my stones dry overnight before putting them away. Never happened again. Likely it's some mineral being dissolved from the stone and seeping out.

Some synthetic whetstones contain aluminium oxide, so it might be oxidation. If the stone is natural, then it is mineral (likely calcium) based oxidation (efflorescence).

thanks, its an old stone my friend gave me that was at his grand parents'. I used water and im not sure what they happened to use before i used it. i was thinking it may be a mold or mildew of some kind from the wooden box its kept in as it might not have been completely dry when i put it away.

If you put water on an oiled stone, it'll likely bead up. The oil tends to soak into the stone and is hard to reverse. You probably don't have to worry about it. Just make sure it dries out when you put it away so mold won't build up. I had mold issue before when I stored it in the cardboard box it came in. Again, I didn't dry it completely before putting it away. As long as the stone is sharp and keeps cutting, it's good to go.