The explanation lay all around them, in the plants and fishes.

Calcium did not make up the bones of Kithrupan life forms. Other metals did. The water was strained and sieved clean by biological filters. As a result, the sea shone all around with the bright colors of metal and oxides of metal. The gleaming dorsal spines of living fish — the silvery seedpods of underwater plants — all contrasted with the more mundane green of chlorophyllic leaves and fronds.

Dominating the scenery were the metal-mounds, giant, spongy islands shaped by millions of generations of coral-like creatures, whose metallo-organic exoskeletons accumulated into huge, flat-topped mountains rising a few meters above the mean water mark.

Atop the islands the drill-trees grew, sending their metalripped roots through each mound to harvest organics and silicates from below. The trees laid a non-metallic layer on top and created a cavity underneath the metal mound. It was a strange pattern. Streaker's onboard Library had offered no explanation.

Toshio's instruments had detected clumps of pure tin, mounds of chromium fish eggs, coral colonies built from a variety of bronze, but so far no convenient, easily gathered piles of vanadium. No lumps of the special variety of nickel they sought.

What they needed was a miracle — one which would enable a crew of dolphins, with the aid of seven humans and a chimpanzee, to repair their ship and get the hell out of this part of the galaxy before their pursuers caught up with them.

At best, they had a few weeks to get away. The alternative was capture by any of a dozen not-entirely-rational ET races. At worst it could mean interstellar war on a scale not seen in a million years.

It all made Toshio feel small, helpless, and very young.

Toshio could hear, faintly, the high-pitched sonar echoes of the returning scouts. Each distant squeak had its tiny, colored counterpoint on his scanner screen.