Weird Icon

[Rexwraith]

Apologies if this has already been posted. But I was clearing T1 exterminate and this icon popped up on the minimap while exploring.
https://i.imgur.com/tccW3Rn.jpg

 

It only appears on that part. If I were to go to the lower level, it would disappear. There's a waterrise behind excalibur, so if I were to go there and fall down or go up, the icon would either show that the item or whatever is below or above me. 
https://i.imgur.com/eUYE9cJ.jpg

Anyone can tell me what this is?

 

Thanks!
 

[Wevi]

There is loot behind those walls. The host must press the button in the center of the room. 

[SmashMeat]

That icon shows that there is loot in the area. Either a container, body, or dropped resource. Someone in the squad was likely using the Loot Radar aura (Or was it thief's wit? They both do the same thing) Lockers do not get marked.

[Quiet_Time1]

Its a hidden wall, theres stuff behind there if you get it open

[Rexwraith]

Yea there was a pressure plate way in a corridor way behind me, so I guess that would have opened the wall there then. Thanks for the responses guys! Appreciate it!