Some objects do not fit in any of the four precedings categories of sundial (L-shaped, sloping, semicircular, or concave). These include objects that may be sundials, but are unique, disputed, or unmarked, and objects related to sundials.
Sundial Candidates
Three sundial candidates have been documented in the literature and are given their own entry in the database:
Sundial-related objects
SX Abu Mina: A noteworthy sundial-related object is an inscription presumably from the base of a concave sundial from around Alexandria (Graßhoff (2015), ID 637, says it is now in Abu Mina). The dial was reconstructed by Diels (1920).
Three further objects are "sundial-related" in that they are merkhets, a type of surveying instrument distinguishable from L-shaped sundials only by the absence of hour marks on their upper faces.
SX Berlin ÄM 14085: Sundial-related object "Merkhet" ÄM 14085 in the Ägyptisches Museum, Berlin
SX OIM 12144: Sundial-related object "Merkhet" OI 12144 in the Oriental Institute Museum, Chicago
SX SciM 1929-585: Sundial-related object "Merkhet" 1929-585 in the Science Museum, London
ÄM 14085 is often mentioned in the early literature alongside L-shaped sundials. The history of OIM 12144 (depicted below) was the subject of a paper by Larson (1992).
OIM 12144, a merkhet
Image: Courtesy of the Oriental Institute of the University of Chicago.
Obelisks
We do not include a catalogue of obelisks, because although these monuments can indeed function as sundials (and have been used as gnomons after their relocation), this does not seem to have been a formal use for them in ancient Egypt.