judge as you want, I personally think that something periodic like that, in a commonly used by humans timeframe even, was coming from the thing. By now we'll never know tho
The sound was periodic though. Every 30min interval. One of the guys in the sub is a former marine member. Some other guy from the same marine was interviewed and said this type of signaling, with 30m intervals, was something taught in said marine.
that doesn't even necessarily mean that, the thing could have imploded after they tried signaling
i don't normally like discussing on reddit because people are so fierce for no reason. seems this didn't change