Or so I thought, but it's a crow's nest.

Holographic rarity equipment. ☆☆☆

Let's let the fairies inside since it has a roof!! I'll feel sorry for them if they get smacked by bad weather.

What exactly is this on my rigging?

It looks like this inside.

Voicepipe

Example: Fubuki class destroyer, "Sagiri."

Skilled lookout

Reference: "Warship Mechanism Encylopedia: Japanese Destroyers"