Hymedesmia acerata is a species of marine demosponge in the family Hymedesmiidae.

It has been found in the Azores on pumice stones and fragments of polyparia.

[2] Its growth for is that of extensive plates that are not thin, and are fleshy and smooth.

The first is the ordinary type which are straight, pointed, and of various lengths with fairly brittle thorns.

The other has extremely abundant ectosomes and are long, straight, and tipped.