4 July 2016, 09:17
Thanks for the link. They are the ones I was thinking of but I would have thought that they were climbable by small creatures and the smallest would be able to slip in the gaps.
Skean Dhude
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It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change. - Charles Darwin
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It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change. - Charles Darwin