Just out of interest, I have 2 Cuckoo Marans and their eggs are dark brown and fairly big.
When I first got them they laid medium sized eggs but after a year they have got a lot bigger, are your Marans laying large eggs?
On my previous posts I said I've ordered Roll-away nest boxes, hopefully to eliminate the egg eating, again this morning I watched a got the eggs as they laid them.
I did notice one hen lay and egg and the moment it dropped the one next to her scooped it under her, but I was there and pinched it lol.