Heater/air-con fan attracting debris.

I have a small problem when my fan is on full, at Prescott in the heat I had the fan on full when suddenly there was an almighty noise like something hitting the fan, yes it's actually happenend to me but it's not shit its like a paper mache type material so I removed what looked about the same as a small egg tray in size and feel, so I removed all that I could find but today when messing around cleaning and doing things to the car its done it again anyone any ideas what's going on.

A picture would help .Do you have AC car ?

Yes it does have air con and it has occurred every time I have the fan on full.I'm just in the process of removing the fan again (thank god its easy to get at and remove) it looks and is the same colour of the grey egg trays around about the same texture too.
I think it may have drawn stuff up from the glovebox as I can see through the flap when the glovebox is open right through to daylight where I removed the fan body. Due to an inbalance in the fan it has broken a few fins/blades and the blades are really filthy too.