In studio in your workspace there is a search, say you have a spawn location with a decal, if you search "spawn" you cant access the spawn locations children like the decal.
Use a recursive function.
find = function(object)
for i,v in next, object:GetChildren() do
if v:IsA("Decal") then
print("Found a decal")
end
find(v)
end
end
find(workspace)