The oldest confirmed poem in this form was a written prayer by Thomas Aquinas in the 13th century. These poems have a specific rhyme scheme of ; aabba...
There once was a man from France (a) Who was really the best at breakdance (a) But then he broke his toe (b) So it looked like a crow (b) And never again would he prance (a)
Another way to recognize a limerick poem is that they often start with "There once was..." or "There was once...". They also have stressed words or beats : 1st, 2nd and 4th line have three stressed words each, the 3d and 4th line have two stressed words each
There ONCE was a MAN from FRANCE Who was REALLY the BEST at BREAKDANCE But then he BROKE his TOE So it LOOKED like CROW And NEVER AGAIN would he PRANCE