zfs and virtualization

I am not sure this is the right place to post this, but I currently have a proxmox server that I have a zfs pool on. Well I moved my images to the zfs storage but I believe it creates them as a zvol. I tested OMV and was able to import my zfs pool using the zfs plugin. My issue is the fact virtualbox does not see zvols as a virtual disk, so I cannot run those machines on there. Is there another solution to run those virtual machines or am I just out of luck ?