Congratulations and the virtual gold star to Wilma, Bonnie, Ragged Robin and Sue Garratt who all identified the Horse Chestnut seed, conker.
The reference to knotted string and knuckles was to do with the game of conkers played by children of all ages around the world. More information can be found on Conkers, How to Play This Traditional Game and a report on the World Conker Championships on the BBC News site.
More a close view than a macro this week.
Clue: Clean up arachnid traces.
No prizes. Just for fun.
Answers left in the comments, along with the answer, will be revealed next Monday.
To clap or not to clap.
46 minutes ago