Can somebody explain this to me?

Among the misteries of life (like why the promoter of this blog is not even writing in it ;D), I wonder what did a sink (I guess) and another pipe (I guess again) do in one of the bedrooms...

A picture from June of one of the bedrooms

No other traces of pipes (or similar) have been found in the other bedrooms and I wonder...what was that for!?
Just for making things straight, the holes are nowadays not visible any longer (hope they were closed correctly...)