Measurements on the green bands produced by endolithic algae in the genus Ostreobium (Chlorophyta: Siphonales) within massive coral skeletons indicate:1.

• (1) that the algal bands are farther from the skeletal surface in the tops than sides of heads

• (2) that multiple algal bands in Parites lutea Milne Edwards & Haime have a periodicity (9.5 mm) slightly greater than but within the range of mean annual P. lutea growth rate ( mm/yr, range: 3.5–11.8 mm/yr)

• (3) that algal bands are farther from the skeletal surface in corals with high bulk density, probably because such skeletons transmit more light than low-density skeletons

• (4) that the distance of the algal band from the skeletal surface is inversely correlated with water depth in some corals; and
• (5) that the distance between the algal band and skeletal surface is not correlated with individual coral growth rates.

Calcite, reported to occur in P. lobata Dana and known to precipitate on algal filaments in marine sediments, was not detected in the skeletons of P. lutea, Favia pallida (Dana) or Goniastrea retiformis (Lamarck), suggesting that Ostreobium is not a template for calcite formation in live corals.