More narrow in meaning is "turtle hair," which describes a hedger or waffler unwilling to stick his neck out for anything, and indeed some ethnologists conjecture that the turtle's cowardly habit of pulling in its head and playing dead at the slightest whiff of trouble is at the root of its devaluation in the minds of modern Chinese.
有民俗學者認為，烏龜在現代中國人意識中成為貶抑之詞，是因為一逢風吹草動，它老哥就縮頭縮腦，詐死般不敢動彈。