Close Up 6: Edge of the lava pool?

Last day of BikerBear's challenge, to take shots of things in the house or garden but from different angles and very, very close up.

I'm probably not the only participant thinking, Phew! Glad I don't have to keep racking my brains, trying to come up with good macro subjects! In that respect it's been a real challenge, but it's also been very rewarding and a LOT of fun! Thank you so much, Anni, for setting it up :)

I don't think today's shot will be too difficult to work out, but you never know.... Any guesses?

Have a closer look.

To see other participants' shots, search for the tag CloseUpMacro