Correct! I thought this would have foxed a few on here but obviously not! Yeah, just wrap paper around the rolling pin bit leaving an inch or so at the end, press into the cup and you have a paper pot for growing seedlings. When they are big enough, plant the whole thing in the ground and the paper breaks down without disturbing the root.
Grandad ran his own nursery sister Dr of horticultural lectures for R H S. Father in law helped lay out Liverpool garden Festival in early 80s he was particularly keen on gardening gadgets!