Unmasked: Some of the breadcrumb sponge' s many disguises
Huge numbers of fish and other marine organisms have been named several times over, say scientists trying to tidy up the system for cataloguing ocean life.
The researchers have produced a new World Register of Marine Species.
It contains about 122,500 validated names, and has rooted out some 56,400 confusing aliases in the process.
One Atlantic sponge was found to have 56 Latin names, given by researchers who thought each of its many guises constituted a distinct species.
Halichondria panicea, often called "breadcrumb sponge", first appeared in the taxonomic literature in 1766. It is known to hang on to floats, pilings, and the underside of rocks and smells like exploded gunpowder.
Its over-classification was the worst example found by the project - but by no means was it an exceptional case.
Some 56,400 aliases have had to be sorted out - 32% of all names reviewed.
The Register is part of the on-going Census of Marine Life, a international programme dedicated to classifying what lives in the oceans.
The Census is currently set to run through to 2010, by which time it is estimated there will be about 230,000 marine species known to science and fully described. The ones still unknown - and therefore yet-to-be described - could push the number of marine species on Earth over a million.