More sea turtle remains lie beached along the coastline. This particular set has an abandoned carriage attached to the turtle's shell. Perhaps this creature was driven to the shoreline by unknown beings rather than beaching itself as some of the other remains suggested. Greymist murlocs now make the remains of this creature their home, feasting off the carrion.
In the carriage, you find a box with strange markings on it; perhaps Gwennyth Bly'Leggonde in Auberdine can make sense of it.
I have heard of the kinds of carriages found on the back of the turtle you found. Those I do believe are naga carriages, used both in battle and in transportation of their supplies on to land. The markings on the box you found are of the naga; this would explain their invasive presence in far-northern Darkshore.
I will send this box to Darnassus along with the rest of your discoveries. This is for you - thank you again for your assistance.