What is this thing on my apple tree?

[biscuitcat]

I've seen this weird egg like thing growing on my apple tree - does anyone have any idea what it is? (And if I need to do anything about it!) thank you!

That looks interesting! Fungus or gall would be my guess - in either case I'd just wait and watch.

It's not a little wasps' nest is it?

Like this?

Ooh, just had a read about galls and they can have wasp larvae in them...who knew?