A holey pebble

No, I certainly don’t mean a holy pebble. Nor do I mean a pebble which is wholly a pebble. I mean one with holes through it.

This little pebble, not much more than a centimetre in size in any direction was picked up in the Isle of Wight last month. I had this idea that if I brought it home it might remind me to find out what created five little holes right through this small beach pebble.

image002You can definitely see through two of the holes but trust me, all five go through. We can also see a kind of double bore appearance.

Let’s flip the pebble over.

image004

Again, we have clear vision through two of the holes.

So what makes them? Well I’m still not 100% sure.

There is a good page about holey stones at https://natureinfocus.wordpress.com/2011/04/09/pebbles-with-holes-made-by-sea-creatures/  Jessica who writes this blog tells us they are caused by certain bivalve molluscs, polychaete worms and even sponges. But she then concentrates on the bigger holes made by those molluscs which are called piddocks, But these are small holes so maybe they are made by those worms.

By the way, I don’t think these stones are lucky, magical or anything like that. I just have a desire to know what caused the holes.

Can anyone offer sensible suggestions please?

 

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2 Responses to “A holey pebble”

  1. winderjssc Says:

    These are in fact holes made by marine worms. As the worm etches back into the rock it creates a U-shaped burrow with two imperceptibly connected holes visible on the surface, side by side. One entrance is for drawing water with food particles into the burrow, and one is for expelling waste matter. Once the burrow is abandoned, and the rock breaks and begins to wear away by various natural processes (which happens very easily in softer rocks like chalk), the edges of the holes are also eroded and become blurred or joined to create these dumb-bell or even heart shapes. Further erosion of the rock can make it so thin that the lower parts of the burrows are completely removed and it is possible to see straight through the former worm holes from one side to the other.

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