This can't be good

I noticed this on the main branch of my largest lilac bush as I was checking out my garden. I don't know what it is and while it looks interesting in the photo, I'm pretty sure it can't be good for the lilacs.

[Christine Sztukowski]

I like the patterns

[Carole Sandford]

Looks like fungi to me, but I’m no expert. It is interesting as you say.

[Polly]

Maybe a fungus? But very interesting.

[Susan Wakely]

Definitely a fungus. Great close up.

[Paula Fontanini]

It definitely looks like a fungus of some sort, hopefully it's not harmful! Definitely makes for an interesting photo though!

[Renee Salamon]

Very eerie looking - hope it doesn’t damage your lilac