O.E.D. Definition of detritus
[mass noun]

waste or debris of any kind:the streets were foul with detritus

gravel, sand, silt, or other material produced by erosion.
organic matter produced by the decomposition of organisms.

Under that broad definition I have 2 items in 4 photos

first the skeleton of a dog laying on seaweed.

The others are of the demise of the Sea Jade a sad way for a grand old vessel to meet her end.Hope for her here coming in for a refit

Sadly I think the money run out and she slowly fell apart

all the above are organic materials