I have read posts on here where some chickens have never laid, so I suppose it is possible. All of my hens lay at some point or another, maybe not well, but they make eggs. I've had several wait until well over a year before they laid their first. Later laying is very common in non-production type breeds, like your Marans. They just take longer to mature, which is why commercial egg businesses don't use them as layers. The time of year they're hatched can effect when they lay as well. Her comb isn't very red, so I'm thinking she's just not there yet.
Good luck!
