Access zoo or xts index

I am using zoo objects, buy my question also applies to xts objects. It looks to me like it is a one column vector with an index. In my case the index is the vector of dates and the one column vector my data. All is good except that I would like to access the dates (from the index).

For example I have the following result:

ObjZoo <- structure(c(10, 20), .Dim = c(2L, 1L), index = c(14788, 14789),
                    class = "zoo", .Dimnames = list(NULL, "Data"))
unclass(ObjZoo)
#      Data
# [1,]   10
# [2,]   20
# attr(,"index")
# [1] 14788 14789

I want to get 14789 in a variable or a vector, but I'm not sure how to access it.