In this study the effects of boring activities of Echinometra lucunter along the Caribbean coast of Colombia and of Echinometra vanbrunti in the Colombian Pacific is examined. Several species inhabit the boreholes occupied by these urchins. The associates live underneath the echinoid on the bottom of the borehole, where they find shelter from exposure and predators. The co-inhabitants of E. lucunter include the porcellanid Clastotoechus vanderhorsti, the brittlestar Ophiothrix synoecina, and the clingfish Acyrtus rubiginosus. The species co-occurring with E. vanbrunti include the porcellanid crab Clastotoechus gorgonensis and the clingfish Arcos decoris.