Nature's evolution was clear to see. The primitive jellies and the chambered nautilus, still remarkably well adapted, had, if not given way, at least made room for improbably wonderful and bizarre adaptations. Diving inside a cave at Blue Holes, a dive site about an hour's boat ride south of Koror, I spied a clam attached to a rock. Inside, an orange Frankensteinian electrical current appeared to be leaping between invisible positive and negative poles. "A flame scallop," our guide told us. "We call it the disco-party clam."