Piles of wood, or heaps of stone and bones driven into or heaped on the soil, formed the support of the crannoge.
They were used as places of retreat or concealment, and are usually found near the ruins of such old forts or castles as are in the vicinity of lakes or marshes.

Sometimes they are connected with the mainland by a causeway, but usually there is no appearance of any; and a small canoe has been, with but very few exceptions, discovered in or near each crannoge.
Since the investigation of these erections in Ireland, others have been discovered in the Swiss lakes of a similar kind, and containing, or rather formed on, the same extraordinary amount of bones heaped up between the wooden piles.
The peculiar objects called celts, and the weapons and domestic utensils of this or an earlier period, are a subject of scarcely less interest.
The use of the celt has fairly perplexed all antiquarian research.

Its name is derived not, as might be supposed, from the nation to whom this distinctive appellation was given, but from the Latin word _celtis_, a chisel.

It is not known whether these celts, or the round, flat, sharp-edged chisels, were called _Lia Miledh_, "warriors' stones." In the record of the battle of the Ford of Comar, Westmeath, the use of this instrument is thus described:-- "There came not a man of Lohar's people without a broad green spear, nor without a dazzling shield, nor without a _Liagh-lamha-laich_ (a champion's hand stone), stowed away in the hollow cavity of his shield....

And Lohar carried his stone like each of his men; and seeing the monarch his father standing in the ford with Ceat, son of Magach, at one side, and Connall Cearnach at the other, to guard him, he grasped his battle-stone quickly and dexterously, and threw it with all his strength, and with unerring aim, at the king his father; and the massive stone passed with a swift rotatory motion towards the king, and despite the efforts of his two brave guardians, it struck him on the breast, and laid him prostrate in the ford.