True, but we also evolved to fear things like molds. They do tend to be rather hazardous to our health, except when they're antibiotics of course. Maybe if the mold ate the type of minerals they themselves were composed of they would have a reason for concern. But I'm thinking actual fear wouldn't come unless this thing was found to be somehow detrimental.
I'm guessing they would begin experimenting to see exactly what allowed for this strange new thing to occur: a combination of certain minerals and water? They'd likely do the logical thing and start seeing what about this area made it special, from the large scope down to the atomic level. Then they'd need to experiment and see if they could recreate it in an isolated area, and grow samples to see what could stop or change it.
It would depend on their definition of living.
Things that make them different from the surrounding world: self-replication, movement, use of resources. The mold also has all these things. They would see it as different doubtlessly, a smaller and possibly less efficient form, but recognizably "alive" in their robotic context.
Yes, I think for something to be considered 'life', most scientists require that it not depend on something else considered 'life' for the materials it needs to replicate. Consuming other organisms is one thing, but invading cells to borrow the replication toolbox is not allowed.
Still, though, when you think about it, at some point there must have been a very complex molecule that was essentially a replication toolkit that couldn't do anything other than replicate other replication toolkits. That thing would have been the first 'life' by most definitions, although it also would have been nothing more than a very complex molecule. It's difficult to think of it as 'alive'.