Heimdallia is an ichnogenus comprising a strange planar trace that does not have a circular cross-section; its maker may have been fed upon by Beaconella.[1]
The trace was probably made by a small crustacean.[2]
References
^McNamara, K.J.; Trewin, N.H. (1993). "A euthycarcinoid arthropod from the Silurian of Western Australia". Palaeontology36: 319–335.