There are instances of crop circle formations that bear binary coded messages, similar to the ones which were transmitted by the SETI, the institution that searches for extraterrestrial intelligence into the space way back in 1974. The same field has another crop circle formation that resembled a face. There is another instance of such combination of binary coded message and face (this time of an alien directly) in crop circles that strengthen the theory of the crop circles being made by the aliens.
Reasons that are put forward by proponents
The reasons that are given by people as a justification of alien connection to crop circles are given below:
(1) Most of the crop circles are huge in scale and carrying out the activity of flattening the crops at such a large scale is not possible humanly.
(2) In most cases the crops are not being cut, but they are being bent without breaking. It would require a lot of calculated effort to bend the crops like this, which seems to be a challenging task for humans
(3) The most important point is the time was taken to create the crop circles. In most cases, the crop circles are believed to have been created overnight! It is not possible for even a team of hundred people to carry out such a humongous task at such a large scale in pitch darkness at such a short time unless they are aliens.