The Caistor-by-Norwich astralagus is a roe deer astragalus found in an urn at Caistor St. Edmund, Norfolk, England. The astralagus is inscribed with a 5th-century Elder Futhark inscription, reading ᚱᚨᛇᚺᚨᚾ raïhan "roe". The inscription is the earliest found in England, and predates the evolution of the specifically Anglo-Frisian Futhorc. As the urn was found in a cemetery that indicated some Scandinavian influence, it has been suggested that the astralagus may be an import, perhaps brought from Denmark in the earliest phase of the Anglo-Saxon settlement of Britain. The inscription is an important testimony for the Eihwaz rune and the treatment of Proto-Germanic *ai. The h rune has the Nordic single-bar shape ᚺ, not the Continental double-bar ᚻ which was later adopted in the Anglo-Frisian runes.
- dated AD 425-475 by Hines 1990:442.
- Waxenberger, Gaby (2006). "The Yew-Rune and the Runes Haglaz, Gyfu, Ior, and Is in the Old English Corpus". In Stoklund, Marie; Nielsen, Michael Lerche; et al. Runes and their secrets: Studies in Runology. Museum Tusculanum Press. pp. 385–414. ISBN 87-635-0428-6. pp. 389-91.
- Bammesberger, A. 'Das Futhark und seine Weiterentwicklung in der anglo-friesischen Überlieferung', in Bammesberger and Waxenberger (eds.), Das fuþark und seine einzelsprachlichen Weiterentwicklungen, Walter de Gruyter (2006), ISBN 3-11-019008-7, 171–187.
- Hines, J. 'The Runic Inscriptions of Early Anglo-Saxon England' in: A. Bammesberger (ed.), Britain 400-600: Language and History, Heidelberg (1990), 437–456.