Neopetrosia subtriangularis is a species of marine petrosiid sponges native to the waters off Florida and the Caribbean Sea.

[4] The branches are brown, beige, yellow or orange in coloration on the external surfaces, though they may possess a greenish tinge.

[5] The openings (oscules) are round and 2 to 4 mm (0.079 to 0.157 in) in diameter, usually surrounded by a rim of paler colored (usually white or yellow) membrane.

[5] Neopetrosia subtriangularis are found in shallow reefs and seagrass beds at depths of greater than 3 m (9.8 ft).

[8][9] Neopetrosia subtriangularis is found off the east and west coasts of Florida, the Bahamas, and throughout the entire Caribbean Sea.