Many second processors come in a cheese wedge casing, but here is my collection of uncased second processors:

Torch Z80 Currently unused	ARM7 Co-Processor In Station 1	65C102 Co-Processor In Station 200	65C102 Co-Processor In my Domesday Machine
ARM7 External Co-Processor Currently unused	Watford Co-Pro Adapter Currently unused	65C102 Co Processor In Station 114	PiTubeDirect In use in Stations 114 and 201
RISC PC Turbo 6502	KL Pi Tube Adapters	Tesco Cheese Biscuits Wedge October 2020	PiTube Gecko
Tesco Cheese Biscuits Wedge PSU Re-Cap	Tube Host ROMs