Yeah, but you may want to be careful attacking them- there's a bug where after you defeat them, your whole planet surrenders to the non-existant enemy.
Best solution is to drop troops and let them defend instead.
BTW, you think the Precursors are bad, you should see some of the other spoilers...
By the way, with the exception of Precursors, all other spoiler races always use the same picture on the diplomacy screen.