I ended up using the tutorial on: http://woshub.com/how-to-access-vmfs-datastore-from-linux-windows/
Thanks to @SmallLoanOf1M for pointing me on the right direction. At first 'fdisk' do not return the partition type because it was in GPT mode, and 'fdisk' does not work with those. And the command 'parted -l' does not returned the partition type of all of the ESXi hard drive.
I needed to install the package vmfs-tools:
apt-get install vmfs-tools
But since I was using ESXi 5.5 the vmfs-tools package was outdated and didnt had the support for VMFS 5, so I needed to install it manually:
wget http://mirrors.kernel.org/ubuntu/pool/universe/v/vmfs-tools/vmfs-tools_0.2.5-1_amd64.deb
dpkg -i vmfs-tools_0.2.5-1_amd64.deb
After that, to mount the HDD was as easy as:
mkdir /mnt/vm_hdd
vmfs-fuse /dev/sdb3 /mnt/vm_hdd
cd /mnt/vm_hdd
To read the virtual hdd inside the datastore I used 'guestmount'.