Help ID these organisms


New member
Hi guys!
Totally new to reefing and just bought an already set-up ecosystem form a guy. Spend some good hours reading and I need you help to identify these organisms.

Image 1 (please ignore Ventricaria)

In this image, just above the leather coral there is some red and some green algae with long thick "branches". Does anyone know what does are called and if they are nuisance algae? Should I get rid of them?

Image 2

I guess the white thing on the rock is a nicely growing sponge tree, in which case I'll keep it (tell me if I'm wrong). However, below it is some BLUE thing which seems like a coralline algae but I'm not sure if such thing exists? Also there are some yellowish things just left form the sponge. Does anyone have any idea what those are?

Sorry for all the noob questions and I hope you guys can help me.

Thank you!