Wot Issit?

Just found these photos on the camera.  This weird stuff was stuck to our washing line in, probably, mid-autumn.  It appears to be organic, was hard, but could be squashed and oozed slightly when you did.

I can only think it’s some kind of eggs, but of what creature?  What lays it eggs in such neat lines completely around the supporting structure.  I’m guessing something thought our washing line was a bit of plant.

Any suggestions?