very green poo

After checking the girls this morning and letting them out I discovered lots of very green poo solid - not runny - it's not quite kryptonite looking but really really green.
They all appear perfectly well and running and scratching about as usual. There's  so much of it and in their house as well so I think its all of them - I was wondering if its due to the red cabbage I gave them yesterday thats caused it but just wanted to put my mind at rest that its not anything else??