Simple Summary: Evolution provided animals with efficient predatory and defense mechanisms that may include the secretion of bioactive molecules, referred to as toxins, that disrupt physiological processes in their recipients. Owing to their reactivity and, often, relative specificity, toxins hold biotechnological interest, especially proteinaceous toxins, which may be more easily manipulated and synthetized in vitro. Here, we investigated putative cysteine-rich neurotoxins from the marine worm Eulalia ('phyllotoxins') and other bioactive proteins by isolating their full coding sequence and analyzing their potential mode of action using computational methods. The findings suggest that some of these toxins can be highly bioactive and that their specificity may render them interesting for further investigation as painkillers, anticoagulative drugs, or even as a method of enhancing the effect of other drugs. Proteinaceous toxins are peptides or proteins that hold great biotechnological value, evidenced by their ecological role, whether as defense or predation mechanisms. Bioprospecting using bioinformatics and omics may render screening for novel bioactives more expeditious, especially considering the immense diversity of toxin-secreting marine organisms. Eulalia sp. (Annelida: Phyllodocidae), a toxin bearing marine annelid, was recently shown to secrete cysteine-rich protein (Crisp) toxins (hitherto referred to as 'phyllotoxins') that can immobilize its prey. By analyzing and validating transcriptomic data, we narrowed the list of isolated full coding sequences of transcripts of the most abundant toxins or accompanying bioactives secreted by the species (the phyllotoxin Crisp, hyaluronidase, serine protease, and peptidases M12A, M13, and M12B). Through homology matching with human proteins, the biotechnological potential of the marine annelid's toxins and related proteins was tentatively associated with coagulative and anti-inflammatory responses for the peptidases PepM12A, SePr, PepM12B, and PepM13, and with the neurotoxic activity of Crisp, and finally, hyaluronidase was inferred to bear properties of an permeabilizing agent. The in silico analysis succeeded by validation by PCR and Sanger sequencing enabled us to retrieve cDNAs can may be used for the heterologous expression of these toxins. [ABSTRACT FROM AUTHOR]