It looks like a Wheel Arch (mudguard) piece, #50745


This is the KRE-O 10162, which first appeared in a blue version from the early version of KRE-O Transformers Optimus Prime Dino Hauler, working as a ball for the midsection of the truck. Sadly, this has later been altered to be black. White and gray versions can be found below: USS Missouri: https://www.hasbro.com/common/documents/...


This is Wheel Hard Plastic with Small Cleats and Flanges (64712). This element in Olive Green color was part of a single set. While Black colored one was included in 18 sets.


As far as I can tell, each arch half is made out of: 40379 Dinosaur tail end section 28870 Plant stem curved 4733 Brick 1x1 with studs in four sides 15208 Plate 1x2 with 3 teeth 49668 Plate 1x1 with tooth 37762 Cylinder 1x1.333 2x 43888 Brick 1x1x6 round with square base 35480 Plate 1x2 with round ends There might be a 25269 1x1 round tile, quarter between ...


This is one of Eastern Germany's (DDR) two brick systems (created by typical VEBs and I'd be suprised if you find those letters anywhere printed on the bricks): most likely Formo because of the simplicity of the backside and how basic all the bricks are - you should not be able to combine it with Lego bricks and these bricks are rather difficult to ...

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