Older than Sauron?

[Rumil]

I wonder if the Wathcher in the water was one of these 'nameless things' ? (I've always thought of them as the 'disgusto-monsters' from D+D, green slime, carrion crawlers etc.!)

This raises an interesting point about Sauron though. As I understand it, the Valar and Maiar were created before Arda, so Sauron must be older than anything of middle earth. However, perhaps Gandalf was counting from when Sauron entered Arda.

The 'nameless things' must surely have been created (or twisted) by Melkor, so does this mean that Sauron was a relative latecomer (in maiar terms) to Arda?