This is on the outside of the tube. There is a series of small dots marks about 1-2mm apart, and one of them has turned into a puncture.
I've felt around the inside of the wheel, and the inside of the rim. Everything feels normal.
I thought maybe the inner tube had turned, and the spoke had poked through, but the marks seem too close together to be caused by the spikes.
Anyone got any ideas? I'm wondering if its safe to just put another tube in?