Excellent photo, Burmese!
Great lighting, focus, depth of field, neutral grey background, file compression.
If I was to be picky, I could say I don't know the size of the coin. (But I do use coins for scale myself - because they have the useful property of always indicating their diameter, even when seen obliquely.)
It is the remains of a serpulid worm tube on a quartz-rich pebble (granitic or quartzitic).
Yours is a modern one (the pebble is modern, so the item on its surface is modern).
But they also occur as fossils, eg. http://www.nhm.ac.uk/nature-online/earth/fossils/article-cyclical-fossil-record/index.html and http://paleo.cc/ce/tracefos.htm (search for 'Serpulid').
Thank you for your prompt response. I'm glad it is something as I seemed to be the only one who could see what I thought were body parts!
Thanks for mentioning the photo. Took it with my ipad using a dinner plate as background. Very technical. Isn't 5 pence always the same size?
Ah - it's the technique more than the tools, then!
Reminds me of a demonstration by Lee Trevino, using every club in his bag to hit a golf ball to the same spot on a green
Your 5 pence piece will now be visible to folks all over the world, many of whom have no idea of its size, and have no access to one to measure it. The 1p coin I use has the same limitation. (I use it partly because the dots near the edge are 0.5mm apart.) We are given a partial excuse, however, because one can look-up the dimensions of coins on the internet these days.
Sometimes an accurate scale is important; at other times it is enough to give a general idea of size. Obviously, your coin is fine for the latter.