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Since amber is highly valued for making jewellery, men today burrow into the hillsides to look for it. The shafts are steep and may go as far as 100 metres into the mountain. The amber miners may have to chisel away tons of stone before they find the particular layer where the lumps of amber acculmulated. But once they find that seam, they often discover piece after piece. It's difficult to tell what's inside pieces like this when they've just bee dug out, because the surface is all pitted and dirty, but when they're polished they may reveal the most extrordinary things. Many pieces are quite clear, with nothing whatever in them, and those are the ones that are valued for jewellery. But one in every dozen or so has the remains of some kind of creature. Back-boned animals were mostly strong and large enough to pull themselves free of the resin if they touched it, but occasionally they failed and these are the rarest of all amber fossils - a tiny lizard and a frog. Insects are the commonest and were sometimes caught in action - an ant carrying a pupa; a bug beside a leaf from which it migh have been sucking sap; a beetle walking up a twig; flying insects with even their delicate wings undamaged; and a whole swarm of ants, so perfectly preserved that you can even see the facets in their 30 million year old eyes.