Vessa turned the feeder cradle over and struck its roof with her knuckles.
The shell was broader than Aylin's shoulders and deep enough for her to crouch beneath. Its open mouth faced the floor. Old cloth packed the joints along its back, but nothing sealed the lower rim.
"It keeps air because water has to climb into it," Vessa said. "Keep the mouth down and the roof up. Tip it, and you give the air away."
"How much air?" Aylin asked.
"Enough for feeding a wounded swimmer through a bad gate. Nobody built it for conversation."
Dust shifted beyond the fracture.
"That is a terrible description of the thing you want her to enter," Jiang called.
"I don't want her in it. She asked how it works."
Vessa tied a dry twist of gray cloth beneath the cradle's roof, then lowered the empty shell through the shelf opening. Water swallowed the rim. Bubbles escaped from an old seam in the back, slowed, and stopped.
