Hybrid pools have an 8" concrete bottom covered with 5/8" of marcite with 3' or 4' fiberglass walls. They were popular in the Midwest in the late 1970's and early 1980's. They were manufactured by Ft. Wayne pools and marketed under the name Starlite and were rolled fiberglass with an acrylic finish. Many hybrid pools were also manufactured by Hallmark. At the time there were lots of manufacturers making these pools with gelcoat and different methods of wall support. There are no builders today of hybrid pools and few people who know how to maintain them.
Ft. Wayne pools can often be identified by the style of coping and embossed tile design which would mean its a acrylic finish on the walls.
Hallmark pools often has logos on the steps. Industry trivia - Mark Hall was one of the founders of Hallmark.
Hybrid pools have reached the point where they need help, and pool professionals have no idea of how to care for them. They develop leaks in the panel transitions where the rubber seals are.
If you have inherited a hybrid pool you have a few options:
- Stick with the pool as it was made. Replaster the floor, replace or repair the fiberglass walls. If there's no longer a builder that does this type of construction in your area you'll have a hard time finding someone to tackle the walls but you never know. Aquabond DKM 5000 or 3M 5200 Marine Adhesive/Caulk has been used to repair cracks in the walls.
- Patch and paint the whole thing as described in this thread. It's a quick fix, lasts for a few years and then you're back in the same boat. If you do a DIY job it's definitely the least expensive but it will continue to be a headache. 
- You can insert a vinyl liner. This is a complicated task. You have to do a VERY thorough measurement of the pool because it's basically a freeform bottom. The cost is more than doing paint DIY, comparable to hiring someone to repaint, and will have the lifespan of a vinyl liner (10-15 years if installed and cared for properly).
- Construct gunite walls on top of the concrete floor and build a traditional plaster pool within the shell. creating a rebar mesh all around the interior wall, driving it into the concrete base and using the old fiberglass panels as the backstop. The pool got smaller in size but it was now a gunite/plaster pool. The story about that build begins on post #79 in this thread.
- this thread chronicles an aborted attempt at covering a hybrid pool with ecoFinish Aquabrite.