According to Round el al. (THE DIATOMS, Biology & Morfology of de Genera, pag.560), “ A marine group commonest in the epipelon of sandy sediments”.

Thanks Sir 

@Jimenez Sir I was just seeing the reference that you have provided but it is not there in that particular page 560. So if can please send me the pdf of the page mentioning it then I will be helpful. 

Perhaps this is a cold water, benthic, salt tolerant diatom species. 

It marine species and go through this link

http://www.algaebase.org/search/species/detail/?species_id=d6ad7e8359e203342&sk=0&from=results

Thanks Dr Bhattacharjee and Mr. Behera for the help. 

Madam if you can provide me a reference of cold water, benthic, salt tolerant diatom then it would be helpful.

Enough guesswork. If you follow the name back to the original -- Navicula investigata Heiden in Schmidt -- which you can trace either through the basionym given in Round et al. p. 672 or through the very useful Catalogue of Diatom Names (http://researcharchive.calacademy.org/research/diatoms/names/index.asp?xAction=getrec&close=true&TaxonCode=16841) you can then look it up in Schmidt's Atlas (plate 258, fig. 6) to discover that it is recent, marine, from Java (Indonesia). The habitat is not specified there (as usual!) but given Lyrella's usual habitat probably on sand. Where did you find yours, Arindam?

I got it in the sediments that were deposited around 4 million years before from northeast Indian ocean. So I want the modern ecology of the species to compare with. 

Good luck with finding the ecology. The trick is to find if anyone has seen it since Heiden!  I found it in Hustedt's Kieselagen, pp. 466-467, but the only additional information there is that he also saw a specimen from Nosi-Be, Madagascar, so he characterizes it as tropical, "seldom seen". Most of the samples that H. looked at do not have habitat data, so it could have been in a mangrove, in sediments on a coral reef, or sediments in a sea grass meadow.. or not associated with sediments. No telling.  It's even possible that these rare sightings could have been of fossil material eroded and resuspended!  I checked a few tropical floras (there aren't many!) with no luck.  It's distinctive enough that I know I have not yet encountered it in Guam.  Best wishes.