‘Banging’ noises heard during desperate search for missing Titanic sub

Grim. 😭

This is one of the few news stories I've followed in my life that has made me feel myself physically reacting to how horrifying it is. Absolute, undiluted, unironic nightmare fuel.

I have two questions to this:

1. How accurately could they triangulate the position the sound is coming from if they drag a sonar/mic around?

(1.b) How long would that take to coordinate?

2. Could the banging be something other than the sub? Just something rolling around on the sea floor / moving back and forth with a regular / periodic current, an animal etc.?