White spot on Duncan?

[ReefJedi]

This white spot on the stem of my Duncan keeps growing. It was about a third of the size a week ago. Should I be concerned?

 

[BadPanda]

I don't know what it is but it happened to my three head duncan as well. The only thing I can think of was my torch touching it. I lost one head 48-72 hrs later. The other two heads looked like crap but were still eating. My duncan I think took about 4 months to recover an now has grown into 8-10 heads from the original two. I was going to cut the head that died but decided to keep as my duncan's battle scar. Maybe put some super glue to prevent it from progressing??