Many predators find the spicules of Homaxinella balfourensis distasteful but the sea stars Odontaster meridionalis and Odontaster validus feed on it, leaving behind the spongin which provides a fibrous support to the sponge.
The main ones are Hlemmur and Lækjartorg in downtown Reykjavik; the others are at Hamraborg in Kópavogur, Fjörður in Hafnarfjörður, Ásgarður in Garðabær, Ártún, Mjódd, Spöngin in Reykjavík and Háholt in Mosfellsbær.