The odontostomatid ciliate Saprodinium from the freshwater portion of transitional estuarine Peconic River. It measures 60 um in diameter. Imaged in Nomarski DIC using Olympus BH2S under SPlan 40x objective plus variable phone cropping.

Saprodinium Lauterborn, 1908
Class Polyhymenophora: Subclass Spirotricha: Order Odontostomatida Family Epalxellidae
Jaggedly rounded, laterally compressed body with a thick, rigid armour composed of numerous pellicular folds and ridges. There is a deep, wide (almost as wide as body) terminal invagination surrounded by 8 spines. The terminal spines tend to be of different lengths and each ends in a needle-like extension. Usually an anterior spine to the anterior edge (dorsal keel). Somatic complex present as 5 upper single rows and 2 lower double rows of cilia. The 5 upper rows are located on a distinct prominence of the armour. Buccal cavity with tooth-like projection on anterior edge. Macronucleus in one to three parts. Sapropelic.

https://www.mikroskopie-forum.de/index.php?topic=21295.0

https://www.nies.go.jp/chiiki1/protoz/morpho/ciliopho/saprodin.htm#Saprodinium%20dentatum