But wait there's more... #Echinochrome staining from eating sea urchins is also known in sharks such as this Crested Horn Shark (#Heterodontus galeatus). #TheMoreYouKNow.
📷: Dr.Bill Gladstone

While #echinochrome staining of bone is best known in sea otters that feed on sea urchins, it is also known in fishes that have a similar diet. Here are a few examples of fishes with purple bones (e.g., Wolffish, Moray Eel & Knifejaw). #TheMoreYouKNow.
https://en.wikipedia.org/wiki/Echinochrome_A