A puzzle... or a band. take your pick.

Something puzzling, mysterious or inexplicable. A riddle, or a difficult problem. ...so says the wictionary.

Enigma is something we do not understand to well. Something that is not clear or not completely clear.

a mysterious or puzzling person or thing. ORIGIN Greek ainigma ‘riddle’. http://www.askoxford.com/concise_oed/enigma?view=uk mystery: somebody or something that is not easily explained or understood http://encarta.msn.com/encnet/features/dictionary/DictionaryResults.aspx?refid=1861608527 Definition: something that defies explanation Synonyms: mystery, secret, puzzle, paradox, perplexity Antonyms: answer, truth, clarity Tips: In the history of cryptography, the Enigma was a portable cipher machine used to encrypt and decrypt secret messages. Today, an enigma is something that's difficult, if not impossible, to explain--something obscure and mysterious. Enigma is a good word to use for things that are rare and puzzling. Enigma is similar in meaning to paradox and anomaly. Enigma is best used to describe a mystery--either a person or something that is not easily explained or understood. A paradox is more of a puzzle or a contradiction; for example, "the famous paradox of what came first, the chicken or the egg." Finally, an anomaly is an irregularity that seems to differ from the norm. You will often hear anomaly used in a statistical context: if statistically something is supposed to happen, but it doesn't, it's usually characterized as an anomaly. The related adjective is enigmatic, which means "hard to understand or interpret." Usage Examples: Her enigmatic smile made me wonder what was on her mind. (mysterious) adjective How such an inept person became CEO for a major corporation, is truly an enigma. (mystery, perplexity) Everyone joked that it was an enigma that the perpetually late employee made it to work on time. (mystery, paradox) He's very difficult to figure out; an enigma, really. (puzzle, mystery) http://vocabulary-vocabulary.com/dictionary/enigma.php ENIGMA (Gr. aivvyµa), a riddle or puzzle, especially a form of verse or prose composition in which the answer is concealed by means of metaphors. Such were the famous riddle of the Sphinx and the riddling answers of the ancient oracles. The composition of enigmas was a favourite amusement in Greece and prizes were often given at banquets for the best solution of them (Athen. x. 457). In France during the 17th century enigma-making became fashionable. Boileau, Charles Riviere Dufresny and J. J. Rousseau did not consider it beneath their literary dignity. In 1646 the abbe Charles Cotier (1604-1682) published a The word is applied figuratively to anything inexplicable or difficult of understanding. http://www.1911encyclopedia.org/Enigma