Thread: Help understanding unions

I was reading through a C++ template whose purpose was to allocate memory blocks (_type_ is the generic type passed). It seems to me the purpose of this code would be to create a byte aligned buffer to store a _type_ object, but I am confused as to why, since buffer is not a pointer, the other elements are not.

Code:

#define CONST_MAX( x, y )  ( (x) > (y) ? (x) : (y) )
#define BLOCK_ALLOC_ALIGNMENT 16
...
union element_t{
  _type_*    data; // this is a hack to make sure the save game system marks _type_ as saveable
  element_t* next;
  byte       buffer[(CONST_MAX(sizeof( _type_ ), sizeof(element_t *)) + (BLOCK_ALLOC_ALIGNMENT - 1)) & ~(BLOCK_ALLOC_ALIGNMENT - 1)];
};