These islands are still being built by a volcanic hotspot that never moves

The Galápagos Islands formed over a stationary plume of magma called the Galápagos hotspot, as the Nazca tectonic plate drifts slowly southeast above it. Older islands drift away from the hotspot and erode, while new ones are still forming above it today — the islands have never been connected to any mainland, which is why their wildlife evolved in such isolation.

— Wikipedia contributors, Galápagos Islands — Galápagos hotspot