The Life of Illtud* has a slightly different version of the Wonder, though it is obviously based on the list or a shared source...

One day as he was sitting at the mouth of the cave, he saw a skiff coming and approaching the shore. When it had reached the shore, he saw two very honourable men in the skiff rowing, and one altar supported by the divine will above the form of the skiff. Saint Illtud went to meet it, uttering words of welcome with gladness. And they after a little conversation gave the sweet smelling body of a certain most holy man to saint Illtud, revealing his name, and after revealing they forbade him ever to divulge it. And so, the body having been consigned to the blessed Illtud, they returned. These things done, he took the body and the altar which had been above the form of the most holy man, and buried it honourably in the cave, the altar being placed over the buried body held up by the divine will as it had been before, by means of which numerous miracles were performed on account of its sanctity.

The main differences, translation and précising aside, are the "Odour of Sanctity" around the corpse, the lack of deadly consequences for those testing the wonder (though they may be the "numerous miracles"), and the fact that the man is buried in the cave itself and there is no church built.

Although the Historia is older than the Life in a complete sense, there are sufficient differences between the accounts to make the relative dating of these sections ambiguous. It is therefore unclear as to whether a church was built, though the general location remains the same in both accounts.

The "Odour of Sanctity" (Info) is a common theme in saint's lives, including the "Celtic" saints. The smell is usually described as sweet and health giving: according to St.Tatheus' Life* (Translation) his body gave off a mellifluous odour...its sweetness, as tasting of a honey-comb as his soul passed on while St.Kentigern's odour (Translation of 12th C. Life*) is described as a fragrant cloud...exceeding all fragrances, poured over all who were assembled with an unimaginable sweetness, and imparted complete health to many, though, equally the smell is metaphorically described thus: fragance of his virtues spread like the odor of life far and wide, his rivals derived an odor of death from this life-giving aroma. The metaphor ultimately derives from 2 Cor 2:14-16 (see also Song of Solomon, eg. 1:2-4):

14But thanks be to God, who always leads us in triumphal procession in Christ and through us spreads everywhere the fragrance of the knowledge of him. 15For we are to God the aroma of Christ among those who are being saved and those who are perishing. 16To the one we are the smell of death; to the other, the fragrance of life. And who is equal to such a task? [New International Version]

Sometimes this smell was associated with ritual action: for example when St.Kentigern "celebrated the sacred mysteries"* However, the smell is more often associated with the bodies of the saints after death. St.Tatheus' has been mentioned above, and St.Patrick also had a postmortem odour. His 6th C. Tripartite Life (Translation) quotes in this respect Gen 27:27 : Ah, the smell of my son [Jacob] is like the smell of a field that the Lord has blessed. The Odour was used as an informal indicator of sainthood for some time, but was finally formally investigated by Prospero Cardinal Lambertini (later made Pope Benedict XIV, 1675-1758), in the chapter De Cadaverum Incorruptione of his definitive De Beatificatione Servorum Dei et de Beatorum Canonizatione. He noted that while dead bodies may not smell bad, for them to smell good was a sign of supernatural agency, and therefore an acceptible sign of sanctity if accompanied by a generally holy life*.

W.A.Hammond (Biography) was apparently the first to suggest this odour had a physiological cause brought about by madness (Ellis, Vol.4, Smell, Section III*), though one would have thought the extreme asceticism of many of the saints would have cause similar corruption: for example, see the following from the life of Kentigern:

...breaking his fast after three or even four days, he would rather revive than restore his body by tasting common and very light foods, namely bread and milk, or cheese, or butter and pottage, lest the inner animal fail after the way of this mortal life. Indeed that I may speak more fitly, by mortifying his members on this earth with the torment of the cross for a long time, he consecrated himself to God by sacrificing a living offering, a sweet smell, pleasing to God.

For example, a fruity smell can be associated with people with ketoacidosis, caused by very poor diet especially in diabetics. Under very poor diet and/or low levels of insulin, fat is metabolised in preference to glucose and this gives of ketones as a byproduct** (this may have been suggested for the Odour by J.B.S.Haldane (Biography), though a reference is not forthcoming).