perhaps a tick bite? 

This could be a remnant of an ectoparasite or the pathologic response to an ectoparasite bite, as Maurizio suggested.  It doesn't really resemble any avian mite or louse that I can recall seeing, but I don't generally see them after fixation for EM in skin samples.  It could also be something entirely unrelated to ectoparasites, such as a reaction to a foreign body in the skin.  Many pollen grains or algae have robust cell walls that  could provoke a cellular response if lodged in the skin.  Since these can be easily confused with parasites in fecal samples, it seems reasonable to surmise they could also get into scratches in the skin and be retained during processing. JP Caruso, PhD, Veterinary Parasitology, University of Georgia, USA, 1983

Dear Anel

I recommend you to use the service of Diagnostic Assistance of the CDC for Parasites. This is very useful. I have used it before, being a good help.

Please check this link: http://www.cdc.gov/dpdx/contact.html

There, is also the information required to send the images for diagnosis.

Finally, please if you consider this answer appropriate, please upvote it using the green up arrow click. Thanks.

Dear Anel,

In my opinion it is the tip of the egg from a chewing lice parasitic of Ostrich. In this case it seems to be a operculum, in lateral view, of an egg of Struthiolipeurus sp. (Phthiraptera, Ischnocera, Philopteridae). I am not sure if you have the operculum entire in the photo, but is pretty expectable that it be broken or smashed. The upper (in your photo) opening is clearly a air chamber and you can see the micropyle inside it.

See the Fig. 52 and 53 (pag. 77) in Mey (1998):

https://www.researchgate.net/publication/230109508_Zur_Taxonomie_Lebenweise_und_parasitophyletischen_Evidenz_der_Federlingsgattung_Struthiolipeurus_sensu_lato_Insecta_Phthiraptera_Ischnocera

Article Zur Taxonomie, Lebensweise und parasitophyletischen Evidenz ...