Exaiptasia diaphana has a slender brownish or whitish translucent column up to 2.5 cm (1 in) long, girdled by two rows of slits through which acontia (threads armed with nematocysts) can protrude.

It occurs in a range of habitats including shallow areas with hard substrates and mangrove swamps.

[2] Exaiptasia diaphana is a zooxanthellate species and has a symbiotic relationship with dinoflagellates, single celled photosynthetic organisms which are incorporated into its tissues.

[2] Exaiptasia diaphana is easy to keep in the laboratory and is used as a model organism, when it can serve as a proxy for coral which is more difficult to maintain and research.

[4] Sea anemones exhibit great powers of regeneration; lost parts swiftly regrow and E. diaphana can be vivisected in the laboratory and then returned to the aquarium where it will heal.