[Greybeard]

Hi all, whilst replacing discs and pads I noticed a damp area round the flexi hose to solid pipe union in the left wheel arch, I needed to remove the caliper anyway so thought to fix the leak at the same time. So tried disconnecting the union, no go, apparently seized, am I missing something? If you look at the attached pic it shows the upper flexi pipe and lower solid pipe but there's some weird oval spring thing? is this locking the union? or does it just need more muscle? Don't want to bugger it up!