That is an incowl filter and is normal. IMHO what happened is related to the first run with an "OVERSPEED" shutdown condition. Contrary to conventional wisdom the weak point in the turbine, related to RPM is not the wheel but the compressor. The compressor is the limiting factor for RPM topend. That is one reason the manufacturers are going to CNC billet compressors. They are much stronger. I think that your compressor was overstressed during the first overspeed and deformed enough to cause you the next problem. On the next run the weakened and stretched cast aluminum blades deformed even more (especially if it oversped again), made contact with the compressor housing and you see the result. The millisecond that the blades contacted the housing it went into a friction/heat/expansion cycle that caused the compressor to instantly seize. All that considerable energy has to go somewere and that somewhere is what turned your engine into a pretzel.
Unfortunatly there is probably very little left useable of your turbine. The Wheel and NGV might be OK if they didnt touch during the violence. Your chamber is probably ok but that is about it. Shaft, compressor, shaft tunnel, compressor housing, diffuser, can, starter and bearings are done.
In retrospect I would not run a engine that had a overspeed shutdown without a check out by the factory-I know that doesnt help you now though. Sorry, Scotty