concretion or fossil

[anonaddict]

location: aarhus, denmark
found: loose beach rock
units: metric
date: 13/10/2024
tempID: concretion

notes:  found this on the beach, looks like a concretion but im not entirely sure since i found another similar iron rich(?) rocks, but with a trilobite inside. id like confirmation about whether this is indeed a concretion

images:

 

the last one is the trilobite from another rock

 

[Rockwood]

This doesn't look like concretion to me. They could be poorly preserved shells, but I think the rock has been wave tumbled into these external shapes.