Sponges collected from rock pools in south Wales could be a source of new drugs to combat breast and lung cancer, say researchers.
The sponges were collected from the Gower peninsula
A team from the Welsh School of Pharmacy found extracts from the Hymeniacidon sponge contain compounds which can block cancer growth.
Medicinal compounds from marine organisms have traditionally been found in species in warm or tropical seas.
Details were presented to the British Pharmaceutical Conference.
Preliminary lab tests have shown that extracts from the sponge are highly effective at inhibiting growth in human breast cancer and small cell lung cancer cell lines.
Instead of mouths sponges have tiny pores on their outer walls through which water is drawn
Cells in the sponge filter out nutrients from the water as it is pumped through its body and out other larger openings
Sponge cells perform a variety of bodily functions and appear to be more independent of each other than are the cells of other animals
Lead researcher Dr Alex White said the sponges had been dried out, and then ground into a powder.
This enabled the scientists to extract compounds to test on cells - but at this stage it was still unclear exactly which of the extracts had a positive effect.
Dr White said: "The sponge is made up of a complex mixture of compounds.
"The next step is to try to characterise the natural products responsible for the anti-proliferative properties and to identify lead compounds for further development.
"It is not uncommon to find extracts from marine organisms, especially sponges, which have this type of activity.
"But British sponges, and their medicinal properties, are largely unexplored and have untapped potential for the discovery of new drugs."
Dr Kat Arney, of Cancer Research UK, said: "Creatures and plants from the sea are a rich source of potential anti-cancer agents, and these results suggest there are possible new treatments hiding within British sea sponges.
"But the research is still at a very early stage and these experiments have only been done in laboratory-grown cells.
"Scientists need to discover precisely which molecules within the sponge are responsible for the effects and how they work.
"They will then need to find out if they have an anti-cancer effect on tumours in humans."
Dr Sarah Rawlings, of the charity Breakthrough Breast Cancer, agreed.
She said: "Although this research is certainly fascinating, it's too early to say whether compounds from these sponges could be used to treat breast cancer patients.
"More work is needed but studies like this are to be welcomed as they are important in helping find possible new treatments for the future."
Dr Emma Pennery, a nurse consultant with the charity Breast Cancer Care, said: "We know from talking with women affected by breast cancer every day that this research will be met with interest."