Question

beaming light deep inside their bodies may explain why some sponges grow to such large sizes, and develop rounded shapes. to grow big, sponges need essential nutrients such as carbon, nitrogen and other metabolites. these are provided by smaller organisms such as algae and cyanobacteria with which the sponges have a symbiotic relationship. because these smaller organisms need light to survive, they usually live on the outside of sponges.

in 1994, researchers discovered that algae sometimes do live deep within the bodies of sponges, creating a mystery as to how they survive there. the answer, as brummer’s team confirmed, is that they live off the light beamed down to them.

...modified article originally by matt walker

Explanation:

Since no specific question is provided about this text, it's not possible to give a targeted answer. If you want to know about the biological concepts here (like symbiosis, sponge - algae relationships), or have a question about summarizing, analyzing the text, etc., please clarify your question. For example, if you want a summary:

The text explains that beaming light inside sponges' bodies might account for some sponges' large size and rounded shape. Sponges need nutrients like carbon and nitrogen, which are provided by smaller organisms (algae, cyanobacteria) they have a symbiotic relationship with. These smaller organisms usually live on sponge exteriors as they need light, but in 1994 it was found algae can live deep in sponges, and Brummer’s team confirmed they survive by using the light beamed to them.

Answer:

The text discusses how light reaching inside sponges may explain their large size/rounded shape, their symbiotic nutrient - providing relationship with smaller organisms (algae, cyanobacteria), and how algae deep in sponges survive (using beamed light), with a 1994 discovery and Brummer’s team’s confirmation.