[2] As with all diatoms, the siliceous cell wall (frustule) consists of two interlocking components ("like two halves of a petri dish"[24]), the hypotheca and the epitheca.

[5] Diatoms in the species S. costatum can be identified by the persistent presence of a 1:2 junction, and the closed tubules of its intercalary fultoportulae processes[5].

[23] If cultured in freshwater, S. costatum develops short intercellular processes[30] and is observed to seemingly not have space between sibling valves at 1 psu.

[33] It is found around the world, including off the coasts of Hong Kong Island,[1] Florida, USA, Uruguay, Brazil,[5] Northern Queensland, Australia,[33] China, and the Sea of Japan.

[34][26] Skeletonema costatum primarily resides in the neritic zone and is commonly found in brackish waters as opposed to the more oceanic, S.

[44][45] Skeletonema costatum is one of the dominant species responsible for red tide outbreaks[6] and blooms frequently occur in the Yangtze River estuary and adjacent waters in China.

[30] The strains of S. costatum from the Sea of Japan off the coast of Dōkai Bay prefer warmer temperatures, and are only collected from water above 20 °C.

[58] Skeletonema costatum blooms in eutrophic waters that are often loaded with nitrogen, phosphorus, and other nutrients/minerals in both dissolved and particulate forms.

[8] High concentrations of nitrates and phosphates increase the amount of inorganic carbon in the form of bicarbonate fixed by S.

[8][60] Iron is an essential nutrient in primary production as it is used in processes of photosynthesis and is under high competition among marine diatoms.

[62][63] Upon infection of S. costatum, ScosV spends about less than 48 to 80 hours reproducing in the cytoplasm before causing lysis of host cells at a burst size range of 90 to 250 infectious units/cell.

[62][63] Marine diatoms account for about 20% of the world's primary production[64] and considering that S. costatum is one of the most abundant species blooming in the ocean indicates that it is one of the major producers of oxygen.

[66] Eutrophic waters, as a result of aquaculture operations in nearshore marine environments such as shrimp farms,[67] create especially favorable conditions for S. costatum growth.

[59] These conditions lead to decreased abundance in other phytoplankton species and have potential in impacting the ecosystem in the area where the bloom occurs.

[14][20] When exposed to stress conditions such as depleted silicon and phosphate concentrations and high irradiation, it produces neutral lipids like triacylglycerol (TAG) which are ideal for making biofuel.

[12] These TAGs are extracted and converted to fatty acid methyl esters (FAME), which are molecules comprising the biofuel, using direct transesterification.

[12][13][72] Skeletonema costatum is also a source of natural products, which are secondary metabolites produced by microorganisms that can be used in pharmaceutical applications.

[73] The extracts of this diatom were found to have prospective use as a central nervous system relaxant that acts like an anti-dopaminergic drug with anticholinergic effects.

[74] Aside from these, antibacterial active compounds extracted from S. costatum using ethanol and methanol were also found to inhibit certain human pathogens, such as Staphylococcus aureus, Proteus mirabilis, and Vibrio cholerae.