When I was a kid playing runescape, I saw this slab with an Black Mask indent on it. The first time I got a Black Mask, I remember trying to interact with
Cave Horror OSRS Guide: The Fabled Black Mask - Rune Fanatics
YC Black Mask With Bamboo Charcoal – Shajgoj
Black mask - The RuneScape Wiki
Black h'ween mask - OSRS Wiki
Runescape 3] Ironman Episode 7: 1500 Total Level + Black Mask! - YouTube
OEM Disposable Black Surgical Mask, Number of Layers: 3 at Rs 3 in Kalpetta
Black mask - OSRS Wiki
Cave Horror OSRS Guide: The Fabled Black Mask - Rune Fanatics