The genus superficially resembles Tetraedron. T. trigonum could well be the species, although with that in mind I believe it belongs to the genus Tetraedriella (http://protist.i.hosei.ac.jp/PDB/Images/Heterokontophyta/Tetraedriella/sp_04.html), but, the image needs to be taken with a better focus and resolution to resolve the uncertainty. It is definitely not Pseudostaurastrum.