The specific epithet circumpulla refers to the shiny black ring formed by pigment in the top part of the margin of the apothecium that encircles the paler disc.

[1] The crustose thallus of Bacidina circumpulla comprises firm squamules (scales) that can be discrete, contiguous, or overlapping.

Individual squamules are up to 350 μm wide with a pale grey, yellowish, or brownish color.

Pycnidia are scattered across the surface, immersed in the thallus with a protruding ostiole that is 60–100 μm in diameter.

It has been found growing on a decaying polypore fungus, and the exposed, soft rotting wood of a log near the seashore.