Stainless shimstock under frag

[Coachp]

This is a new one for me. I bought a toadstool a couple of months ago and its mostly moved off of the plug. However underneath it I found a square of stainless shim. It seemed it was used to mount frag with super glue to the plug. Is this a common practice? normally i buy local or on rubble rock sorry for the rough pics morning blues
First picture is of the shim stock
Second is where it was under the coral on the plug

 

[fishguy242]

wow ,that's a first for me,30+ yrs reefing hope never see again!!