The monstrous whale known as aspidochelone was characterized by two distinctive behaviors. First, the whale possessed the ability to entrap its prey, usually fish, through the emission of a sweet, seductive odor released from its mouth. Unsuspecting fish were attracted by the scent, only to be devoured when the whale’s cavernous mouth snapped shut.
– “Bad to the bone”?  The Unnatural History of Monstrous Medieval Whales 

This poem is so fun to say aloud and it nearly is sensible:

Cethegrande is a fis, / The moste that in water is. / That thu wuldes seien get, / Gef thu it soge wan it f let, / That it were a neilond / That sete one the se sond. / This fis that is unride, / Thanne him hungreth he gapeth wide; / Ut of his throte it smit an onde, / The swetteste thing that is o londe. / Therfore othre fisses to him dragen. / Wan he it felen he aren fagen. / He cumen and hoven in his muth; / Of his swike he am uncuth. / This cete thanne his chaveles luketh, / Thise fisses alle in suketh. /
– Middle English Bestiary (British Library Arundel MS 292) [13th century]