This is one of two very similar species of sundials. The shells are difficult to tell apart, but the animal coloration is consistently quite different. The other species has a couple of dark brown to black longitudinal streaks on the head and anterior tentacles. One of them is Architectonica modesta and the other A. perspectiva. We are not certain which is which, but think the one below with the paler colored animal is A. modesta. They can be seen at various muck sites, particularly Anilao Pier at night.
Created 11 February 2020