I recently needed a 3d model of a crab and found that some similarly obsessive user over at Sketchfab had created dozens (possibly hundreds?) of extremely detailed crab models -- at 500k - 1.5 million tris, so basically unusable for most typical animation needs, but they're beautifully detailed and free for download.

My first thought was that it might be the same person, since they had a Japanese username! But I don't think it actually is; the Sketchfab person has all kinds of natural models. Here's the account in case anyone is interested: https://sketchfab.com/ffishAsia-and-floraZia/models