Question: Unusual brood pattern??

[bluetruckhoney]

I am a new beekeeper and last week picked up a ten frame hive that a local beekeeper installed five franes(Nuc) in my new hive. Activity around the hive this part week has been very active. I went in the hive today and noticed this unusual(In my opinion, but remember I'am new) pattern. The foundation appeared to be recessed/withdrawn around the edges and then a large round clump of drawn comb. This does not look like a swarm cell as all around the raised area are cells just as on a normal frame. Can anyone tell me if this is normal or what this is. Also, I noticed plenty of capped brood, larvae, eggs, pollen, nectar, but I did not see the queen. Let me know what you think. I'am trying to attach a picture but I have not figured this out yet. Hopefully this will be coming soon. Thanks!

[Michael Bush]

A picture would help. I'm guessing they have bullet shaped tops and they are drone cells. But without that in your description or a picture, I am only guessing.