The mullets swim alongside the bottom of the boat and I am assuming feed on the crap growing there
They bang into the boat when scared (which is every 14 seconds) and it sounds like someone is hitting the boat or someone is knocking on the boat.
Apparently mullets are nocturnal or just never sleep.
This went on until I don't know what time, but very late or very early in the morning.
Since it is not a consistant noise it wakes me up ~ sort of an internal warning system from spending so much time at anchor.