Merging objects in Unity

Hello,

At this moment I am working on a group-project game. We didn't have a lot of experience in Unity, so we messed some things up. For instance, we used a tile-based structure to create our level.

This tile-based structure is the thing that is causing us headaches right now. The problem is that every model we created, in our scene, has their own Game Object. This means that for every piece of wall, decoration asset etc we have an object which explodes the number of draw calls needed.

So my question is this: Is it possible to merge these objects as 1, or perhaps exporting the meshes as 1 object so that we can re-import it as one? Maybe someone else knows another approach to this particular issue?

Kind regards,

Max