Halecium pusillum is a small hydroid found in the Mediterranean but has circumglobal
distribution. It was found in the intertidal zone growing on the brown alga Cystoseira sp.
The photographic material taken at the time is unfortunately not of the expected quality.
However the specimen listed here is described in detail (p. 184 & Fig. 3b) in the following
paper published in 2013 by Soto Àngel and Peña Cantero. This species was identified by
the same authors.