a hornless ox or a horned horse—neither fish nor fowl; nondescript;unfounded hearsay ? ～，不古不今。(楊雄《太玄·更》)A hornless ox or a horned horse—it never exists in times,ancient or modern.
童牛角馬tónɡ niú jiǎo mǎ
童牛：無(wú)角的牛；角馬：長(zhǎng)了角的馬。比喻違背常理的事物。unfounded hearsay, neither fish nor fowl