It appears that the mounting plate for the CSMU on the DFDR chassis has suffered some deformation, and there is stress indication which looks like the CSMU securing bolts have been dragged through the mounting plate.
The CSMU/ULB will not be too far away, i.e. the combo will be a straight down unit, but mass/volume means their landing will not have been soft. The silty bottom indicates to me that some technique other than visual will be needed to find them