Coprolite? from Cretaceous

[drhelixnebula]

Hi everyone!
I found these among soft gray mudstones. From south Ankara, Turkey. Maastrichtian age, Late Cretaceous. Readings indicate that the area was shelf/fluvial at that time. Coprolite or pseudocoprolite? Some sort of mineral/mud concretion? Any guess? Some of them have tiny broken shell parts, sand grains inside and cracked crust as you can see in the picture. Please help me identify these. :) Thanks.

[Rockwood]

Sorry, these are ironstone concretions. 

[ynot]

Agree with iron concretions.