Whats up with my wood?

I bought two pieces of driftwood a while back, around 5 months or so. In the past month I have noticed that the bigger piece seems to be peeling for a lack of a better term. There are several clumps of shavings (again for a lack of a better term) of the wood on my substrate. Since I use sand it is quite noticeable, has anyone else have this happen to them and how can I prevent this?

 

Is it possible that is a brown algae? Sometimes new-ish tanks get this brown, almost powdery looking algae.

 

I think some types of wood are known to peel like that...Malaysian, maybe? I don't remember. Do you know what kind it is?

 

Is it the bark coming off? Do you have a Pleco that is gnawing on the wood. Mine leaves slivers on the substrate.
carol

 

Yes I forgot to mention that it is Malaysian driftwood. I had plecos but the peeling starting before then.

 

I have Malaysian Driftwood, and pieces slough off all the time. In my 10 gallon, my Clown Pleco helps seed that long lol