So far, it's enclosed. That limits what can get in here. And I don't hear anything ahead.

[She wasn't going to mention exactly how good octopi and squid were at getting through small openings. Not having bones or much of a shell was an advantage there.]

[S'reee sang out a few louder notes, getting a sense from the echoes of their path. Actually, the algae was slightly worrying to her: things in the abyss didn't glow unless they had a reason, and that reason usually was to attract attention. But it was possible that the city bred such plants deliberately, and it had just escaped to live in the tunnels underground.]