It's the result of shedding bits of the intestines Meg. It's normal. What caught me out was I have never seen it from a chick that age before. Talking to the chicken club this morning its more common at this age than I thought. I took a sample.@Shadrach what do you suppose is wrong with the chick? Was that blood in the picture?

One might think the chick had coccidia, but coccidia blood tends to be redder and spotty.
I've seen all three chicks poop both cecal and normal poop a few times since and all the poop looks okay.
One of the guys mentioned that mistaking this for coccidia and treating as if it was coccidia within 24 hours of such a shed can damage the intestines.
I'm very impressed with the knowledge of most of the chicken club members.
One guy for example has a left footed hen. How many people would even notice that.
His left footed hen has the eye functions reversed as well.
If you watch your hens going up a ramp at roost time for example the right footed and eyed hens will all jump onto the ramp on the left side, right eye and right foot closest to the ramp. Quite a few chicken keepers here have coops well off the ground. It makes it much harder for predators and rats in particular to get in; plus you can inspect the underside of the coops.