Hi guys,
Thanks for the input. After a hour of searching on the net, I come to the conclusion that they are probably just plain crystals.
The reasons is that all surface mounted crystal oscillators I found so far have connections along the length of the module instead of at the ends.
At least two sources suggested that the reason for two connections at each end in the above image is because customers can order the package with internal crystal connections at both ends or at one end to suit their circuit design.
Thanks