It is endemic to the Mediterranean Sea,[1] and is commonly known as the Neptune-grass bryozoan because it is exclusively found growing on seagrasses, usually on Neptune grass (Posidonia oceanica), but occasionally on eelgrass (Zostera marina).

[2] Electra posidoniae is a white bryozoan forming encrusting colonies of zooids on the leaves of seagrasses.

Electra posidoniae is the most common bryozoan on P. oceanica in the Mediterranean in the depth range 15 to 30 m (50 to 100 ft).

[3] Bryozoans feed on diatoms and organic particles which the lophophores extract from the water flowing past.

The embryos are brooded in a membranous pouch inside the zooid for a while and then have a planktonic larval stage lasting several months, during which they can disperse widely.