Technical blocks/Skull

Java Edition
1.4.2	12w36a	Heads have an extra, unobtainable item form corresponding to its block ID. It can be obtained via the `/give` command or inventory editors with numeric item ID 144.
		Unlike the proper head items at the time, it had a placement sound, and was capable of directly replacing replaceable blocks. (The proper head items could only replace them indirectly, i.e. they could be placed against the side of a block which would result in it replacing snow, however could not replace snow if the snow itself was targeted.)
		The head item, if placed by a player facing north, east, south or west would result in the placement of a skull block with metadata 0, 1, 2 and 3, which were, in order, an east-facing skull visually wall attached but with a floor hitbox, a north-facing floor skull, a north-facing wall skull and a south-facing wall skull.
1.7.2	13w37a	The direct item form of heads has been removed from the game. It can no longer exist as an item in any way, only as a placed block.
Pocket Edition Alpha
?		Skulls exist as an item.

Java Edition
1.4.2	12w36a	The skull item uses this texture in inventories, when held in first or third person view, as a dropped item or when in an item frame.
1.5	13w02a	The skull item is now completely invisible in inventories.
		The skull item causes a game crash when held in first or third person view, as a dropped item or when in an item frame.
		This is due to major texture storage changes in this version.
	13w02b	The skull item now uses this texture in inventories, when held in first or third person view, as a dropped item or when in an item frame.

12w36a - 13w25b: [Has no defined name, rendering a minimum-length text box if highlighted]
13w25c - 14w21b: tile.skull.name

When given using the /give command, it is announced as tile.skull.name.

References