Looks fine, try not to stress

Maybe an alien life form is trying to burst out..

It looks fine to me but also looks pregnant.

I don't see anything abnormal.

One of my seed grown tangerines put out a 3 inch sharp thorn that sprouted at the tip and grew leaves and stem. Trees do strange things.

Thankyou everyone for your comments - I've done some more research and it seems I have citrus gall wasp laying eggs in my tree. So nikthegreek, you aren't completely wrong about the lifeforms trying to burst out! And poncirusguy, it is pregnant, with baby wasps :(

Ps. this wasp is native to Australia and apparently common in Melbourne where I live - it used to only live in the northern part of the country but has spread all the way down here now

Thank you for the update. We learned something new today. I was pretty sure something was wrong with the tree.

Frances thank you for your pictures. I wasn't observant enough to notice anything odd. Once you pointed out the problem, I Googled it to read up on the pest. Very interesting indeed.