Common clownfish in a sea anemone, Raja Ampat Islands, Indonesia

Reefside roommates. Common clownfish in a sea anemone, Raja Ampat Islands, Indonesia

Sea anemones may look like underwater flowers, but they're actually animals—close relatives of jellyfish and corals. Anchored to rocks or reefs, they use a sticky base and a crown of waving tentacles armed with tiny stingers to capture passing prey. Those stings can paralyze small fish, yet one famous neighbor is immune.

In the image, a common clownfish peeks out from its sea anemone home in Indonesia's Raja Ampat Islands, a remote archipelago at the heart of the Coral Triangle, known for extraordinary marine diversity. The clownfish's special mucus coating protects it from harm, allowing it to shelter safely among the tentacles. In return, the fish helps deter predators and drops food scraps the anemone can eat. In the reefs of Raja Ampat, moments like this play out everywhere—quiet alliances that keep the waters humming with life.