Mud horse versus Grass Mud Horse

We start with the "mud horse," which I encountered in a Neatorama post.  It's a sled-like device used by fishermen to transport collection baskets and supplies to their nets staked at the low-tide limits.   The flat bottom distributes the weight, allowing for more efficient movement than carrying materials on one's back.   Such devices have apparently been used since time immemorial on the tidal flats of the English coast.

The top photo shows a mud horse (with basket and nets) from an exhibit at the British Museum.  Below that is Adrian Sellick, reposted by the Telegraph to be the last mudhorse fisherman in England -

Mr Sellick, a father-of-four, fears the mud-horse method will be lost forever when he finally gives up as there is currently no one interested in learning the trade...

'It is difficult work, you lie on your belly on it and push with your feet across the beach, but you sort of pick up techniques from watching.  I don't believe you could do it unless it was in your blood, I am the fifth generation of my family to use the mud-horse and I could never give it up.'' 

A large photoset showing Mr. Sellick at work is posted at grovelinda's Flickr photostream.

While researching that topic, I kept encountering unrelated material about a "grass-mud horse," such as this YouTube video (subtitles NSFW)(content repeats after 0:53):

This rather bizarre entity is explained at China Digital Times, first with these lyrics:

There is a herd of Grass Mud Horses*
In the wild and beautiful Ma Le Desert**
They are lively and intelligent
they are fun-loving and nimble
They live freely in the Ma Le Desert
They are courageous, tenacious, and overcome the difficult environment

Oh lying down Grass Mud Horse
Oh running wild Grass Mud Horse
They defeated river crabs*** in order to protect their grass land
River crabs forever disappeared from Ma Le Desert

and these footnotes:

* Grass Mud Horse (草泥马) is phonetically equivalent to “F**k Your Mother!” in Chinese
** Ma Le Desert (马勒戈壁) is phonetically equivalent to “Your Mother’s C**t”
*** “River Crab (河蟹) ” is phonetically equivalent to “harmony (和谐).” Chinese netizens say their deleted posts have been “harmonized,” or “eaten by the river crab.” So “river crab” became a code name for internet censors. 

So the song and the videos and the phrase "Grass-mud horse" are vehicles used to protest internet censorship in the P.R.C.

“Grass Mud Horse (草泥马)” is not an uncivilized word and is not officially banned, therefore it can be sung publicly. Although many people use “Grass Mud horse” as an alternative curse or just use it randomly, this word and its deviant expression already generated a pattern of discourse and sub-culture. “Grass Mud Horse (草泥马)” represents such information and opinions which cannot be accepted by the mainstream discourse, and “the Song of the Grass Mud Horse” has become a metaphor of the power struggle over Internet expression.

This alpaca-like animal appears to be the representation of a grass mud horse:

and this CNN video from last year summarizes the entire meme:

I expect TYWKIWDBI will now be banned in China...