Forgery. Probable core of plated denarius. Alternatively, it could be a smaller denomination struck in bronze.

Die-axis: 6 o’clock
Weight: 3.09 grammes

IMP CARAVSIVS P F AVG, Laureate, draped and cuirassed bust of Carausius, right. (obverse)

[EXPE]CTATE VEN[I], Britannia (wearing mural crown) clasping hands with Carausius. (reverse)

Thank you British Museum for images and text
https://www.britishmuseum.org/collection/object/C_2000-1201-1